# Selina solutions for Concise Chemistry Class 10 ICSE chapter 5 - Mole concept and Stoichiometry [Latest edition]

## Chapter 5: Mole concept and Stoichiometry

Exercise 5AExercise 5BExercise 5CExercise 5DMiscellaneous Exercises
Exercise 5A [Pages 75 - 76]

### Selina solutions for Concise Chemistry Class 10 ICSE Chapter 5 Mole concept and Stoichiometry Exercise 5A [Pages 75 - 76]

Exercise 5A | Q 1.1 | Page 75

State : Gay-Lussac's Law of combining volumes.

Exercise 5A | Q 1.2 | Page 75

Exercise 5A | Q 2.1 | Page 75

What do you mean by stoichiometry?

Exercise 5A | Q 2.2 | Page 75

Define atomicity of a gas. State the atomicity of Hydrogen, Phosphorus and Sulphur.

Exercise 5A | Q 2.3 | Page 75

Differentiate between N2 and 2N.

Exercise 5A | Q 3.1 | Page 75

Explain Why?

"The number of atoms in a certain volume of hydrogen is twice the number of atoms in the same volume of helium at the same temperature and pressure."

Exercise 5A | Q 3.2 | Page 75

Explain Why?

"When stating the volume of a gas, the pressure and temperature should also be given."

Exercise 5A | Q 3.3 | Page 75

Explain Why ?

Inflating a balloon seems to violate Boyle's law.

Exercise 5A | Q 4.1 | Page 75

Calculate the volume of oxygen at S.T.P required for the complete combustion of 100 litres of carbon monoxide at the same temperature and pressure.

2CO + O2 → 2CO2

Exercise 5A | Q 4.2 | Page 75

200 cm3 of hydrogen and 150 cm3 of oxygen are mixed and ignited, as per the following reaction,

2H+ O2  → 2H2O

What volume of oxygen remains unreacted?

Exercise 5A | Q 5 | Page 75

24 cc Marsh gas (CH4) was mixed with 106 cc oxygen and then exploded. On cooling the volume of the mixture became 82 cc, of which, 58 cc was unchanged oxygen. Which law does this experiment support? Explain with calculations.

Exercise 5A | Q 6 | Page 75

What volume of oxygen would be required to burn completely 400 ml of acetylene [C2H2]? Also calculate the volume of carbon dioxide formed.

2C2H2 + 5O→ 4CO2 + 2H2O (l)

Exercise 5A | Q 7 | Page 75

112 cm3 of H2S(g) is mixed with 120 cm3 of Cl2(g) at STP to produce HCl(g) and sulphur(s). Write a balanced equation for this reaction and calculate (i) the volume of gaseous product formed (ii) composition of the resulting mixture.

Exercise 5A | Q 8 | Page 75

1250cc of oxygen was burnt with 300cc of ethane [C2H6]. Calculate the volume of unused oxygen and the volume of carbon dioxide formed :

$\ce{2C2H6 + 7O2 -> 4CO2 + 6H2O}$

Exercise 5A | Q 9 | Page 75

What volume of oxygen at STP is required to affect the combustion of 11 litres of ethylene [C2H4] at 273o C and 380 mm of Hg pressure?

C2H4+3O2 → 2CO2 + 2H2O

Exercise 5A | Q 10 | Page 75

Calulate the volume of HCl gas formed and chlorine gas required when 40 ml of methane reacts completely with chlorine at S.T.P.

CH4 + 2Cl2 → CH2Cl2+2HCl

Exercise 5A | Q 11 | Page 75

What volume of propane is burnt for every 500 cm3 of air used in the reaction under the same conditions? (assuming oxygen is 1/5th of air)

C3H+ 5O2 → 3CO2 + 4H2O

Exercise 5A | Q 12 | Page 75

450 cm3 of nitrogen monoxide and 200 cm3 of oxygen are mixed together and ignited. Caclulate the composition of resulting mixture.

2NO + O2 → 2NO2

Exercise 5A | Q 13 | Page 75

If 6 liters of hydrogen and 4 liters of chlorine are mixed and exploded and if water is added to the gases formed, find the volume of the residual gas.

Exercise 5A | Q 14 | Page 75

Ammonia may be oxidised to nitrogen monoxide in the presence of a catalyst according to the following equation.

4NH3 + 5O2 → 4NO + 6H2O

If 27 litres of reactants are consumed, what volume of nitrogen monoxide is produced at the same temperature and pressure?

Exercise 5A | Q 15 | Page 75

A mixture of hydrogen and chlorine occupying 36 cm3 was exploded. On shaking it with water, 4cmof hydrogen was left behind. Find the composition of the mixture.

Exercise 5A | Q 16 | Page 75

What volume of air (containing 20% O2 by volume) will be required to burn completely 10 cm3 each of methane and acetylene?

CH4 + 2O→ CO2 + 2H2O

2C2H2 + 5O2 → 4CO2 + 2H2O

Exercise 5A | Q 17 | Page 75

LPG has 60% propane and 40% butane: 10 litres of this mixture is burnt. Calculate the volume of carbon dioxide added to atmosphere.

C3H8 + 5O2 → 3CO2 + 4H2O

2C4H10 + 13O2 → 8CO2 + 10H2O

Exercise 5A | Q 18 | Page 75

200 cm3 of CO2 is collected at S.T.P when a mixture of acetylene and oxygen is ignited. Calculate the volume of acetylene and oxygen at S.T.P. in original mixture.

2C2H2(g) + 5O2(g) → 4CO2(g)+ 2H2O(g)

Exercise 5A | Q 19 | Page 76

You have collected (a) 2 litres of CO2 (b) 3 litres of chlorine (c) 5 litres of hydrogen (d) 4 litres of nitrogen and (e) 1 litres of SO2, under similar conditions of temperature and pressure. Which gas sample will have :

(a) the greatest number of molecules, and

(b) The least number of molecules?

Exercise 5A | Q 20 | Page 76

The gases chlorine, nitrogen, ammonia and sulphur dioxide are collected under the same conditions of temperature and pressure. The following table gives the volumes of gases collected and the number of molecules (x) in 20 litres of nitrogen. You are to complete the table giving the number of molecules in the other gases in terms of x.

 Gas Volume (in litres) Number of molecules Chlorine  Nitrogen Ammonia Sulphur dioxide 10 20 20 5 x
Exercise 5A | Q 21 | Page 76

(i) If 150 cc of gas A contains X molecules, how many molecules of gas B will be present in 75 cc of B?

The gases A and B are under the same conditions of temperature and pressure.

(ii) Name the law on which the above problem is based.

Exercise 5B [Pages 83 - 85]

### Selina solutions for Concise Chemistry Class 10 ICSE Chapter 5 Mole concept and Stoichiometry Exercise 5B [Pages 83 - 85]

Exercise 5B | Q 1.1 | Page 83

The relative atomic mass of Cl atom is 35.5 a.m.u. Explain this statement.

Exercise 5B | Q 1.2 | Page 83

What is the value of Avogadro's number?

Exercise 5B | Q 1.3 | Page 83

What is the value of molar volume of a gas at S.T.P?

Exercise 5B | Q 2.1 | Page 83

Define or explain the term

Vapour density

Exercise 5B | Q 2.2 | Page 83

Define or explain the term

Molar volume

Exercise 5B | Q 2.3 | Page 83

Define or explain the term

Relative atomic mass

Exercise 5B | Q 2.4 | Page 83

Define or explain the term

Relative molecular mass

Exercise 5B | Q 2.5 | Page 83

Define or explain the term

Exercise 5B | Q 2.6 | Page 83

Define or explain the term

Gram atom

Exercise 5B | Q 2.7 | Page 83

Define or explain the term

Mole

Exercise 5B | Q 3.1 | Page 83

What are the main applications of Avogadro's Law?

Exercise 5B | Q 3.2 | Page 83

How dose Avogadro's Law explain Gay-Lussac's Law of combining volumes?

Exercise 5B | Q 4.1 | Page 83

Calculate the relative molecular mass of :

Ammonium chloroplatinate (NH4)2 PtCl6

Exercise 5B | Q 4.2 | Page 83

Calculate the relative molecular mass of :

Potassium chlorate

Exercise 5B | Q 4.3 | Page 83

Calculate the relative molecular mass of :

CuSO4. 5H2O

Exercise 5B | Q 4.4 | Page 83

Calculate the relative molecular mass of :

(NH4)2SO4

Exercise 5B | Q 4.5 | Page 83

Calculate the relative molecular mass of :

CH3COONa

Exercise 5B | Q 4.6 | Page 83

Calculate the relative molecular mass of :

CHCl3

Exercise 5B | Q 4.7 | Page 83

Calculate the relative molecular mass of :

(NH4)2 Cr2O7

Exercise 5B | Q 5.1 | Page 84

Find the

number of molecules in 73 g of HCl

Exercise 5B | Q 5.2 | Page 84

Find the

weight of 0.5 mole of O2

Exercise 5B | Q 5.3 | Page 84

Find the

number of molecules in 1.8 g of H2O

Exercise 5B | Q 5.4 | Page 84

Find the

number of moles in 10 g of CaCO3

Exercise 5B | Q 5.5 | Page 84

Find the

Weight of 0.2 mole of H2 gas

Exercise 5B | Q 5.6 | Page 84

Find the

Number of molecules in 3.2 g of SO2.

Exercise 5B | Q 6 | Page 84

Which of the following would weigh most?

(a) 1 mole of H2
(b) 1 mole of CO2
(c) 1 mole of NH3
(d) 1 mole of CO

Exercise 5B | Q 7 | Page 84

Which of the following contains maximum number of molecules?

• 4g of O2

• 4g of NH3

• 4g of CO2

• 4 g of SO2

Exercise 5B | Q 8.1 | Page 84

Calculate the number of

Particles in 0.1 mole of any substance.

Exercise 5B | Q 8.2 | Page 84

Calculate the number of

Hydrogen atoms in 0.1 mole of H2SO4.

Exercise 5B | Q 8.3 | Page 84

Calculate the number of

Molecules in one Kg of calcium chloride.

Exercise 5B | Q 9.1 | Page 84

How many grams of

Al are present in 0.2 mole of it?

Exercise 5B | Q 9.2 | Page 84

How many grams of

HCl are present in 0.1 mole of it?

Exercise 5B | Q 9.3 | Page 84

How many grams of

H2O are present in 0.2 mole of it?

Exercise 5B | Q 9.4 | Page 84

How many grams of

CO2 is present in 0.1 mole of it?

Exercise 5B | Q 10.1 | Page 84

The mass of 5.6 litres of a certain gas at S.T.P. is 12 g. What is the relative molecular mass or molar mass of the gas?

Exercise 5B | Q 10.2 | Page 84

Calculate the volume occupied at S.T.P. by 2 moles of SO2.

Exercise 5B | Q 11.1 | Page 84

Calculate the number of moles of CO2 which contain 8.00 g of O2

Exercise 5B | Q 11.2 | Page 84

Calculate the number of moles of Methane in 0.80 g of methane.

Exercise 5B | Q 12.1 | Page 84

Calculate the weight/mass of: An atom of oxygen

Exercise 5B | Q 12.2 | Page 84

Calculate the weight/mass of: an atom of hydrogen

Exercise 5B | Q 12.3 | Page 84

Calculate the weight/mass of: a molecule of NH3

Exercise 5B | Q 12.4 | Page 84

Calculate the weight/mass of: 10^22 atoms of carbon

Exercise 5B | Q 12.5 | Page 84

Calculate the weight/mass of: the molecule of oxygen

Exercise 5B | Q 12.6 | Page 84

Calculate the weight/mass of: 0.25-gram atom of calcium

Exercise 5B | Q 13.1 | Page 84

Calculate the mass of 0.1 mole of the following CaCO3

(Ca = 40, Na=23, Mg =24, S=32, C = 12, Cl = 35.5, O=16, H=1)

Exercise 5B | Q 13.2 | Page 84

Calculate the mass of 0.1 mole of the following Na2SO4.10H2O

(Ca = 40, Na=23, Mg =24, S=32, C = 12, Cl = 35.5, O=16, H=1)

Exercise 5B | Q 13.3 | Page 84

Calculate the mass of 0.1 mole of the following CaCl2

(Ca = 40, Na=23, Mg =24, S=32, C = 12, Cl = 35.5, O=16, H=1)

Exercise 5B | Q 13.4 | Page 84

Calculate the mass of 0.1 mole of the following Mg

(Ca = 40, Na=23, Mg =24, S=32, C = 12, Cl = 35.5, O=16, H=1)

Exercise 5B | Q 14.1 | Page 84

Calculate the number of oxygen atoms in 0.10 mole of Na2CO3.10H2O.

Exercise 5B | Q 14.2 | Page 84

Calculate the number of gram atoms in 4.6 gram of sodium

Exercise 5B | Q 14.3 | Page 84

Calculate :
The number of moles in 12g of oxygen gas. [O = 16]

Exercise 5B | Q 15 | Page 84

What mass of Ca will contain the same number of atoms as are present in 3.2 g of S?

Exercise 5B | Q 16.1 | Page 84

Calculate the number of atoms Which is given below :

52 moles of He

Exercise 5B | Q 16.2 | Page 84

Calculate the number of atoms Which is given below :

52 amu of He

Exercise 5B | Q 16.3 | Page 84

Calculate the number of atoms Which is given below :

52 g of He

Exercise 5B | Q 17 | Page 84

Calculate the number of atoms of each kind in 5.3 grams of sodium carbonate.

Exercise 5B | Q 18.1 | Page 84

Calculate the mass of nitrogen supplied to soil by 5 kg of urea [CO(NH2)2] [O = 16; N = 14; C = 12 ; H = 1 ]

Exercise 5B | Q 18.2 | Page 84

Calculate the volume occupied by 320 g of sulphur dioxide at S.T.P. [S = 32; O = 16]

Exercise 5B | Q 19.1 | Page 84

What do you understand by the statement that 'vapour density of carbon dioxide is 22'?

Exercise 5B | Q 19.2 | Page 84

The atomic mass of Chlorine is 35.5. What is its vapour density?

Exercise 5B | Q 20 | Page 84

What is the mass of 56 cm3 of carbon monoxide at STP?

(C=12 ,O=16)

Exercise 5B | Q 21 | Page 84

Determine the number of molecules in a drop of water which weighs 0.09g.

Exercise 5B | Q 22.1 | Page 84

The molecular formula for elemental sulphur is S8.In sample of 5.12 g of sulphur

How many moles of sulphur are present?

Exercise 5B | Q 22.2 | Page 84

The molecular formula for elemental sulphur is S8.In sample of 5.12 g of sulphur

How many molecules and atoms are present?

Exercise 5B | Q 23 | Page 84

If phosphorus is considered to contain P4 molecules, then calculate the number of moles in 100g of phosphorus?

Exercise 5B | Q 24.1 | Page 84

Calculate:

The gram molecular mass of chlorine if 308cm3 of it at STP weighs 0.979 g

Exercise 5B | Q 24.2 | Page 84

Calculate:

The volume of 4g of H2 at 4 atmospheres.

Exercise 5B | Q 24.3 | Page 84

Calculate :
The mass of oxygen in 2.2 litres of CO2 at STP.

Exercise 5B | Q 25 | Page 84

A student puts his signature with a graphite pencil. If the mass of carbon in the signature is 10-12 g, calculate the number of carbon atoms in the signature.

Exercise 5B | Q 26 | Page 84

An unknown gas shows a density of 3 g per litre at 2730C and 1140 mm Hg pressure. What is the gram molecular mass of this gas?

Exercise 5B | Q 27 | Page 84

Cost of Sugar (C12H22 O11) is Rs 40 per kg; calculate its cost per mole.

Exercise 5B | Q 28.1 | Page 84

Which of the following weighs the least?

2 g atom of N

Exercise 5B | Q 28.2 | Page 84

Which of the following weighs the least?

3 x1025 atoms of carbon

Exercise 5B | Q 28.3 | Page 84

Which of the following weighs the least?

1 mole of sulphur

Exercise 5B | Q 28.4 | Page 84

Which of the following weighs the least?

7g silver

Exercise 5B | Q 29 | Page 84

Four grams of caustic soda contains :

• 6.02 x 1023 atoms of it

• 4 g atom of sodium

• 6.02 x1022 molecules

• 4 moles of NaOH

Exercise 5B | Q 30 | Page 84

The number of molecules in 4.25 g of ammonia is :

• 1.0 x 1023

• 1.5 x 1023

• 2.0 x 1023

• 3.5 x 1023

Exercise 5B | Q 31.1 | Page 85

Correct the statement, if required

One mole of chlorine contains 6.023 x 1010 atoms of chlorine.

Exercise 5B | Q 31.2 | Page 84

Correct the statement, if required

Under similar conditions of temperature and pressure, two volumes of hydrogen combined with two volumes of oxygen will give two volumes of water vapour.

Exercise 5B | Q 31.3 | Page 85

Correct the statement, if required

The relative atomic mass of an element is the number of times one molecule of an element is heavier than 1/12 the mass of an atom of "C"^12.

Exercise 5B | Q 31.4 | Page 85

Correct the statement, if required

Under the same conditions of temperature and pressure, equal volumes of all gases contain the same number of atoms.

Exercise 5C [Pages 90 - 91]

### Selina solutions for Concise Chemistry Class 10 ICSE Chapter 5 Mole concept and Stoichiometry Exercise 5C [Pages 90 - 91]

Exercise 5C | Q 1 | Page 90

Give three kinds of information conveyed by the formula H2O.

Exercise 5C | Q 2 | Page 90

Explain the terms empirical formula and molecular formula.

Exercise 5C | Q 3.1 | Page 90

Give the empirical formula of : C6H6

Exercise 5C | Q 3.2 | Page 90

Give the empirical formula of: C6H8O3

Exercise 5C | Q 3.3 | Page 90

Give the empirical formula of : C2H2

Exercise 5C | Q 3.4 | Page 90

Give the empirical formula of: CH3COOH

Exercise 5C | Q 4 | Page 90

Find the percentage of water of crystallisation in CuSO4.5H2O. (At. Mass Cu = 64, H = 1, O = 16, S = 32)

Exercise 5C | Q 5.1 | Page 90

Calculate the percentage of phosphorus in Calcium hydrogen phosphate Ca(H2PO4)2

Exercise 5C | Q 5.2 | Page 90

Calculate the percentage of phosphorus in Calcium phosphate Ca3(PO4)2

Exercise 5C | Q 6 | Page 90

Calculate the percent composition of Potassium chlorate KClO3.

Exercise 5C | Q 7 | Page 90

Find the empirical formula of the compounds with the following percentage composition:

Pb = 62.5%, N = 8.5%, O = 29.0%

Exercise 5C | Q 8 | Page 90

Calculate the mass of iron in 10 kg of iron ore which contains 80% of pure ferric oxide.

Exercise 5C | Q 9 | Page 90

If the empirical formula of two compounds is CH and their Vapour densities are 13 to 39 respectively, find their molecular formula.

Exercise 5C | Q 10 | Page 90

Find the empirical formula of a compound containing 17.64 % hydrogen and 82.35 % of nitrogen.

Exercise 5C | Q 11 | Page 90

On analysis, a substance was found to contain

C = 54.54%, H = 9.09%, O = 36.36%

The vapour density of the substance is 44,calculate;

(a) its empirical formula, and

(b) its molecular formula

Exercise 5C | Q 12 | Page 90

An organic compound, whose vapour density is 45, has the following percentage composition

H=2.22%, O = 71.19% and remaining carbon. Calculate,

(a) its empirical formula, and

(b) its molecular formula

Exercise 5C | Q 13 | Page 90

An organic compound contains H = 4.07%, Cl = 71.65% chlorine and remaining carbon. Its molar mass = 98.96. Find,

(a) Empirical formula, and

(b) Molecular formula

Exercise 5C | Q 14.1 | Page 90

A hydrocarbon contains 4.8g of carbon per gram of hydrogen. Calculate the g atom of each

Exercise 5C | Q 14.2 | Page 90

A hydrocarbon contains 4.8g of carbon per gram of hydrogen. Calculate find the empirical formula

Exercise 5C | Q 14.3 | Page 90

A hydrocarbon contains 4.8g of carbon per gram of hydrogen. Calculate Find molecular formula, if its vapour density is 29.

Exercise 5C | Q 15 | Page 90

0.2 g atom of silicon Combine with 21.3 g of chlorine. Find the empirical formula of the compound formed.

Exercise 5C | Q 16 | Page 90

A gaseous hydrocarbon contains 82.76% of carbon. Given that its vapour density is 29, find its molecular formula.

Exercise 5C | Q 17 | Page 90

In a compound of magnesium (Mg = 24) and nitrogen (N = 14), 18 g of magnesium combines with 7g of nitrogen. Deduce the simplest formula by answering the following questions.

(a) How many gram- atoms of magnesium are equal to 18g?

(b) How many gram- atoms of nitrogen are equal to 7g of nitrogen?

(c) Calculate the simple ratio of gram- atoms of magnesium to gram-atoms of nitrogen and hence the simplest formula of the compound formed.

Exercise 5C | Q 18 | Page 91

Barium chloride crystals contain 14.8% water of crystallization. Find the number of molecules of water of crystallization per molecule.

Exercise 5C | Q 19 | Page 91

Urea is a very important nitrogenous fertilizer. Its formula is CON2H4. Calculate the percentage of nitrogen in urea. (C=12,O=16 ,N=14 and H=1).

Exercise 5C | Q 20 | Page 91

Determine the formula of the organic compound if its molecule contains 12 atoms of carbon. The percentage compositions of hydrogen and oxygen are 6.48 and 51.42 respectively.

Exercise 5C | Q 21.1 | Page 91

A compound with empirical formula AB2 has the vapour density equal to its empirical formula weight. Find its molecular formula.

Exercise 5C | Q 21.2 | Page 91

A compound with empirical formula AB has vapour density 3 times its empirical formula weight. Find the molecular formula.

Exercise 5C | Q 21.3 | Page 91

10.47 g of a compound contained 6.25 g of metal A and rest non-metal B. Calculate the empirical formula of the compound [At. wt of A = 207, B = 35.5]

Exercise 5C | Q 22 | Page 91

A hydride of nitrogen contains 87.5% percent by mass of nitrogen. Determine the empirical formula of this compound.

Exercise 5C | Q 23 | Page 91

A compound has O=61.32%, S= 11.15%, H=4.88% and Zn=22.65%.The relative molecular mass of the compound is 287 amu. Find the molecular formula of the compound, assuming that all the hydrogen is present as a water of crystallization.

Exercise 5D [Page 94]

### Selina solutions for Concise Chemistry Class 10 ICSE Chapter 5 Mole concept and Stoichiometry Exercise 5D [Page 94]

Exercise 5D | Q 1 | Page 94

Complete the following blanks in the equation as indicated.

CaH2 (s) + 2H2O (aq) → Ca(OH)2 (s) + 2H2 (g)

(a) Moles: 1 mole + ------- → -------- + --------------

(b) Grams: 42g + ------- → -------- + ----------------

(c) Molecules: 6.02 x 1023 + -------→-------- + -----------

Exercise 5D | Q 2.1 | Page 94

The reaction between 15 g of marble and nitric acid is given by the following equation:

CaCO3 + 2HNO3 Ca(NO3)2+ H2O + CO2

Calculate: the mass of anhydrous calcium nitrate formed

Exercise 5D | Q 2.2 | Page 94

The reaction between 15 g of marble and nitric acid is given by the following equation:

CaCO3 + 2HNO3 Ca(NO3)2+ H2O + CO2

Calculate: the volume of carbon dioxide evolved at S.T.P.

Exercise 5D | Q 3 | Page 94

66g of ammounium sulphate is produced by the action of ammonia on sulphuric acid.

Write a balanced equation and calculate:

(a) Mass of ammonia required.

(b) The volume of the gas used at the S.T.P.

(c) The mass of acid required.

Exercise 5D | Q 4.1 | Page 94

The reaction between the red lead and hydrochloric acid is given below:

Pb3O+ 8HCl → 3PbCl+ 4H2O + Cl2

Calculate: the mass of lead chloride formed by the action of the 6.85 g of red lead

Exercise 5D | Q 4.2 | Page 94

The reaction between the red lead and hydrochloric acid is given below:

Pb3O+ 8HCl → 3PbCl+ 4H2O + Cl2

Calculate: the mass of the chlorine

Exercise 5D | Q 4.3 | Page 94

The reaction between the red lead and hydrochloric acid is given below:

Pb3O+ 8HCl → 3PbCl+ 4H2O + Cl2

Calculate: the volume of the chlorine evolved at S.T.P.

Exercise 5D | Q 5 | Page 94

Find the mass of KNO3 required to produce 126 kg of nitric acid. Find whether a larger or smaller mass of NaNO3 is required for the same purpose.

KNO3+ H2SO→ KHSO4 + HNO3

NaNO+ H2SO→ NaHSO4 + HNO3

Exercise 5D | Q 6 | Page 94

Pure calcium carbonate and dilute hydrochloric acid are reacted and 2 litres of carbon dioxide were collected at 27oC and normal pressure.

CaCO3 + 2HCl → CaCl2 + H2O + CO2

Calculate :

(a) The mass of salt required.

(b) The mass of the acid required to prepare the 2 litres of CO2 at 27 C and normal pressure.

Exercise 5D | Q 7 | Page 94

Calculate the mass and volume of oxygen at S.T.P., which will be evolved on electrolysis of 1 mole (18g) of water

Exercise 5D | Q 8 | Page 94

1.56 g of sodium peroxide reacts with water according to the following equation:

2Na2O2 + 2H2O4NaOH + O2

Calculate:

(a) mass of sodium hydroxide formed,

(b) The volume of oxygen liberated at S.T.P.

(c) Mass of oxygen liberated.

Exercise 5D | Q 9 | Page 94

(a) Calculate the mass of ammonia that can be obtained from 21.4 g of NH4Cl by the reaction:

2NH4Cl + Ca(OH)2 → CaCl2 +2H2O + 2NH3

(b) What will be the volume of ammonia when measured at S.T.P?

The molar volume of a gas = 22.4 litres at STP.

Exercise 5D | Q 10 | Page 94

Aluminium carbide reacts with water according to the following equation.

Al4C3 + 12H2O → 3CH4 +  4Al(OH)3

(a) What mass of aluminium hydroxide is formed from 12g of aluminium carbide?

(b) What volume of methane s.t.p. is obtained from 12g of aluminium carbide?

Exercise 5D | Q 11.1 | Page 94

MnO2 + 4HCl → MnCl2 + 2H2O +Cl2

0.02 moles of pure MnO2is heated strongly with conc. HCl. Calculate:

mass of MnOused

Exercise 5D | Q 11.2 | Page 94

MnO2 + 4HCl → MnCl2 + 2H2O +Cl2

0.02 moles of pure MnO2is heated strongly with conc. HCl. Calculate: moles of salt formed

Exercise 5D | Q 11.3 | Page 94

MnO2 + 4HCl → MnCl2 + 2H2O +Cl2

0.02 moles of pure MnO2is heated strongly with conc. HCl. Calculate: the mass of salt formed

Exercise 5D | Q 11.4 | Page 94

MnO2 + 4HCl → MnCl2 + 2H2O +Cl2

0.02 moles of pure MnO2is heated strongly with conc. HCl. Calculate: moles of chlorine gas formed

Exercise 5D | Q 11.5 | Page 94

MnO2 + 4HCl → MnCl2 + 2H2O +Cl2

0.02 moles of pure MnO2is heated strongly with conc. HCl. Calculate: the mass of chlorine gas formed

Exercise 5D | Q 11.6 | Page 94

MnO2 + 4HCl → MnCl2 + 2H2O +Cl2

0.02 moles of pure MnO2is heated strongly with conc. HCl. Calculate volume of chlorine gas formed at S.T.P.

Exercise 5D | Q 11.7 | Page 94

MnO2 + 4HCl → MnCl2 + 2H2O +Cl2

0.02 moles of pure MnO2is heated strongly with conc. HCl. Calculate: moles of acid required

Exercise 5D | Q 11.8 | Page 94

MnO2 + 4HCl → MnCl2 + 2H2O +Cl2

0.02 moles of pure MnO2is heated strongly with conc. HCl. Calculate: Mass of acid required

Exercise 5D | Q 12 | Page 94

Nitrogen and hydrogen react to form ammonia.

N2 (g) + 3H2 (g)2NH3 (g)

If 1000g H2 reacts with 2000g of N2:

(a) Will any of the two reactants remain unreacted? If yes, which one and what will be its mass?

(b) Calculate the mass of ammonia(NH3) that will be formed?

Miscellaneous Exercises [Pages 95 - 98]

### Selina solutions for Concise Chemistry Class 10 ICSE Chapter 5 Mole concept and Stoichiometry Miscellaneous Exercises [Pages 95 - 98]

Miscellaneous Exercises | Q 1 | Page 95

From the equation for burning of hydrogen and oxygen

$\ce{2H2 + O2 -> 2H2O}$ (Steam)

Write down the number of mole (or moles) of steam obtained from 0.5 moles of oxygen.

Miscellaneous Exercises | Q 2 | Page 95

From the equation

3Cu + 8HNO3 → 3Cu (NO3)2+ 4H2O + 2NO

(Atomic mass Cu = 64, H = 1, N = 14,O = 16)

Calculate:

(a) Mass of copper needed to react with 63g of HNO3

(b) The volume of nitric oxide at S.T.P. that can be collected.

Miscellaneous Exercises | Q 3.1 | Page 95

Calculate the number of moles in 7g of nitrogen.

Miscellaneous Exercises | Q 3.2 | Page 95

What is the volume at S.T.P. of 7.1 g of chlorine?

Miscellaneous Exercises | Q 3.3 | Page 95

What is the mass of 56 cm3 of carbon monoxide at S.T.P?

Miscellaneous Exercises | Q 4 | Page 95

Some of the fertilizers are sodium nitrate NaNO3, ammonium sulphate (NH4)2SO4 and urea CO(NH2)2. Which of these contains the highest percentage of nitrogen?

Miscellaneous Exercises | Q 5 | Page 95

Water decomposes to O2 and H2 under suitable conditions as represented by the equation below:

2H2O → 2H2+O2

(a) If 2500 cm3 of H2 is produced, what volume of O2 is liberated at the same time and under the same conditions of temperature and pressure?

(b) The 2500 cm3 of H2 is subjected to 2 times an increase in pressure (temp. remaining constant). What volume of H2 will now occupy?

(c) Taking the value of H2 calculated in 5(b), what changes must be made in Kelvin (absolute) temperature to return the volume to 2500 cm3 pressure remaining constant.

Miscellaneous Exercises | Q 6 | Page 95

Urea [CO(NH2)2] is an important nitrogenous fertilizer. Urea is sold in 50 kg sacks. What mass of nitrogen is in one sack of urea?

Miscellaneous Exercises | Q 7 | Page 95

Find the molecular formula of a hydrocarbon having vapour density 15, which contains 20% of Hydrogen.

Miscellaneous Exercises | Q 8 | Page 95

The following experiment was performed in order to determine the formula of a hydrocarbon. The hydrocarbon X is purified by fractional distillation.

0.145 g of X was heated with dry copper (II) oxide and 224 cm3 of carbon dioxide was collected at S.T.P.

(a) Which elements does X contain?

(b) What was the purpose of copper (II) oxide?

(c ) Calculate the empirical formula of X by the following steps:

(i) Calculate the number of moles of carbon dioxide gas.

(ii) Calculate the mass of carbon contained in this quantity of carbon dioxide and thus the mass of carbon in sample X.

(iii) Calculate the mass of hydrogen in sample X.

(iv) Deduce the ratio of atoms of each element in X (empirical formula).

Miscellaneous Exercises | Q 9 | Page 95

A compound is formed by 24g of X and 64g of oxygen. If the atomic mass of X=12 and O=16, calculate the simplest formula of the compound.

Miscellaneous Exercises | Q 10.1 | Page 95

A gas cylinder filled with hydrogen holds 5g of the gas. The same cylinder holds 85 g of gas X under the same temperature and pressure. Calculate :

Vapour density of gas X.

Miscellaneous Exercises | Q 10.2 | Page 95

A gas cylinder filled with hydrogen holds 5g of the gas. The same cylinder holds 85 g of gas X under the same temperature and pressure. Calculate :

The molecular weight of gas X.

Miscellaneous Exercises | Q 11.1 | Page 95

When carbon dioxide is passed over red hot carbon, carbon monoxide is produced according to the equation :

CO2 + C → 2CO

What volume of carbon monoxide at S.T.P. can be obtained from 3 g of carbon?

Miscellaneous Exercises | Q 11.2 | Page 95

60 cm3 of oxygen was added to 24 cm3 of carbon monoxide and mixture ignited. Calculate:

(i) The volume of oxygen used up and

(ii) The volume of carbon dioxide formed.

Miscellaneous Exercises | Q 12 | Page 96

How much calcium oxide is obtained by heating 82 g of calcium nitrate? Also, find the volume of NO2 evolved :

$\ce{2Ca(NO3)2 ->2CaO + 4NO2 + O2}$

Miscellaneous Exercises | Q 13 | Page 96

The equation for the burning of octane is:

2C8H18 + 25O2 → 16CO2 + 18H2O

(i) How many moles of carbon dioxide are produced when one mole of octane burns?

(ii) What volume at S.T.P. is occupied by the number of moles determined in (i)?

(iii) If the relative molecular mass of carbon dioxide is 44, what is the mass of carbon dioxide produced by burning two moles of octane?

(iv) What is the empirical formula of octane?

Miscellaneous Exercises | Q 14 | Page 96

Ordinary chlorine gas has two isotopes 3517Cl and 3717Cl in the ratio of 3:1. Calculate the relative atomic mass of chlorine.

Miscellaneous Exercises | Q 15 | Page 96

Silicon (Si = 28) forms a compound with chlorine (Cl = 35.5) in which 5.6 g of silicon combines with 21.3 g of chlorine. Calculate the empirical formula of the compound.

Miscellaneous Exercises | Q 16 | Page 96

An acid of phosphorus has the following percentage composition; Phosphorus = 38.27%; hydrogen = 2.47 %; oxygen = 59.26 %. Find the empirical formula of the acid and its molecular formula, given that its relative molecular mass is 162.

Miscellaneous Exercises | Q 17 | Page 96

Calculate the mass of substance 'A' which in gaseous form occupies 10 litres at 270C and 700 mm pressure. The molecular mass of 'A' is 60.

Miscellaneous Exercises | Q 18 | Page 96

A gas cylinder can hold 1 kg of hydrogen at room temperature and pressure.

(a) What mass of carbon dioxide can it hold under similar conditions of temperature and pressure?

(b) If the number of molecules of hydrogen in the cylinder is X, calculate the number of carbon dioxide molecules in the cylinder. State the law that helped you to arrive at the above result

Miscellaneous Exercises | Q 19 | Page 96

The following questions refer to one mole of chlorine gas.

(a) What is the volume occupied by this gas at S.T.P.?

(b) What will happen to the volume of gas, if pressure is doubled?

(c) What volume will it occupy at 2730C?

(d) If the relative atomic mass of chlorine is 35.5, what will be the mass of 1 mole of chlorine gas?

Miscellaneous Exercises | Q 20.1 | Page 96

A hydrate of calcium sulphate CaSO4.xH2O contains 21% water of crystallization. Find the value of x.

Miscellaneous Exercises | Q 20.2 | Page 96

What volume of hydrogen and oxygen measured at S.T.P. will be required to prepare 1.8 g of water?

Miscellaneous Exercises | Q 20.3 | Page 96

How much volume will be occupied by 2g of dry oxygen at 270C and 740 mm pressure?

Miscellaneous Exercises | Q 20.4 | Page 96

What would be the mass of CO2 occupying a volume of 44 litres at 250 C and 750 mm pressure?

Miscellaneous Exercises | Q 20.5 | Page 96

1 g of a mixture of sodium chloride and sodium nitrate is dissolved in water. On adding silver nitrate solution, 1.435 g of AgCl is precipitated.

AgNO3 (aq) + NaCl (aq) → AgCl (s) + NaNO3

Calculate the precentage of NaCl in the mixture.

Miscellaneous Exercises | Q 21.1 | Page 96

From the equation :

C + 2H2SO4 → CO2 + 2H2O + 2SO2

Calculate :

1. The mass of carbon oxidized by 49 g of sulphuric acid.
2. The volume of sulphur dioxide measured at STP,  liberated at the same time.
Miscellaneous Exercises | Q 21.2 | Page 96

i. A compound has the following percentage composition by mass: carbon 14.4%, hydrogen 1.2%, and chlorine 84.5%. Determine the empirical formula of this compound. Work correctly to 1 decimal place. (H = 1; C = 12;Cl = 35.5)

ii. The relative molecular mass of this compound is 168, so what is its molecular formula?

Miscellaneous Exercises | Q 22.1 | Page 96

Find the percentage of oxygen in magnesium nitrate crystals [Mg (NO3) 6H2O].

Miscellaneous Exercises | Q 22.2 | Page 96

Find the percentage of boron in Na2B4O7.10H2O. [H = 1, B = 11, O =16, Na = 23].

Miscellaneous Exercises | Q 22.3 | Page 96

Find the percentage of phosphorus in the fertilizer superphosphate Ca(H2PO4)2

Miscellaneous Exercises | Q 23 | Page 96

What mass of copper hydroxide is precipitated by using 200 gm of sodium hydroxide?

$\ce{2NaOH + CuSO4 -> Na2SO4 + Cu(OH)2 ↓}$

[Cu = 64, Na = 23, S = 32, H = 1]

Miscellaneous Exercises | Q 24.1 | Page 96

Solid ammonium dichromate decomposes as :

$\ce{(NH4)2Cr2O7 -> N2 + Cr2O3 + 4H2O}$

If 63 g of ammonium dichromate decomposes. Calculate the quantity in moles of (NH4)2Cr2O7

Miscellaneous Exercises | Q 24.2 | Page 96

Solid ammonium dichromate decomposes as :

$\ce{(NH4)2Cr2O7 -> N2 + Cr2O3 + 4H2O}$

If 63 g of ammonium dichromate decomposes. Calculate the quantity in moles of nitrogen formed

Miscellaneous Exercises | Q 24.3 | Page 96

Solid ammonium dichromate decomposes as :

$\ce{(NH4)2Cr2O7 -> N2 + Cr2O3 + 4H2O}$

If 63 g of ammonium dichromate decomposes. Calculate the volume of N2 evolved at STP.

Miscellaneous Exercises | Q 24.4 | Page 96

Solid ammonium dichromate decomposes as :

$\ce{(NH4)2Cr2O7 -> N2 + Cr2O3 + 4H2O}$

If 63 g of ammonium dichromate decomposes. Calculate what will be the loss of mass?

Miscellaneous Exercises | Q 24.5 | Page 96

Solid ammonium dichromate decomposes as :

$\ce{(NH4)2Cr2O7 -> N2 + Cr2O3 + 4H2O}$

If 63 g of ammonium dichromate decomposes. Calculate calculate the mass of chromium (III) oxide formed at the same time.

Miscellaneous Exercises | Q 25 | Page 97

Hydrogen sulphide gas burns in oxygen to yield 12.8 g of sulphur dioxide gas as under :

2H2S + 3O2 → 2H2O + 2SO2

Calculate the volume of hydrogen sulphide at S.T.P. Also, calculate the volume of oxygen required at S.T.P. which will complete the combustion of hydrogen sulphide determined in (litres).

Miscellaneous Exercises | Q 26 | Page 97

Ammonia burns in oxygen and the combustion, in the presence of a catalyst. May be represented by
$\ce{2NH3 + 2 1/2O2 -> 2NO + 3H2O}$

[H= 1, N= 14, O=16]

What mass of steam is produced when 1.5 g of nitrogen monoxide is formed?

Miscellaneous Exercises | Q 27 | Page 97

If a crop of wheat removes 20 kg of nitrogen per hectare of soil, what mass of the fertilizer, calcium nitrate Ca(NO3)2 would be required to replace the nitrogen in a 10-hectare field?

Miscellaneous Exercises | Q 28 | Page 97

Concentrated nitric acid oxidizes phosphorus to phosphoric acid according to the following equation:

P+ 5HNO3 → H3PO4+ 5NO2 + H2O

If 6.2g of phosphorus was used in the reaction calculate:

(a) The number of moles of phosphorus taken and mass of phosphoric acid formed.

(b) mass of nitric acid will be consumed at the same time?

(c) The volume of steam produced at the same time if measured at 760 mm Hg pressure and 2730C?

Miscellaneous Exercises | Q 29 | Page 97

112 cm3 of a gaseous fluoride of phosphorus has a mass of 0.63 g. Calculate the relative molecular mass of the fluoride. If the molecule of the fluoride contains only one atom of phosphorus, then determine the formula of the phosphorus fluoride. [ F=19, P=31].

Miscellaneous Exercises | Q 30 | Page 97

Washing soda has formula Na2CO3.10H2O. What mass of anhydrous sodium carbonate is left when all the water of crystallization is expelled by heating 57.2 g of washing soda?

Miscellaneous Exercises | Q 31 | Page 97

A metal M forms a volatile chloride containing 65.5% chlorine. If the density of the chloride relative to hydrogen is 162.5, find the molecular formula of the chloride (M = 56).

Miscellaneous Exercises | Q 32.1 | Page 97

A compound X consists of 4.8% carbon and 95.2% bromine by mass.

Determine the empirical formula of this compound working correctly to one decimal place (C = 12; Br = 80)

Miscellaneous Exercises | Q 32.2 | Page 97

A compound X consists of 4.8% carbon and 95.2% bromine by mass.

If the vapour density of the compound is 252, what is the molecular formula of the compound?

Miscellaneous Exercises | Q 33 | Page 97

The reaction: 4N2O + CH4 → CO2 + 2H2O + 4N2 takes place in the gaseous state. If all volumes are measured at the same temperature and pressure, calculate the volume of dinitrogen oxide (N2O) required to give 150 cm3 of steam.

Miscellaneous Exercises | Q 34 | Page 97

Samples of the gases O2, N2, CO2 and CO under the same conditions of temperature and pressure contain the same number of molecules x. The molecules of oxygen occupy V litres and have a mass of 8 g under the same conditions of temperature and pressure

What is the volume occupied by:

(a) x molecules of N2

(b) 3x molecules of CO

(c) What is the mass of CO2 in grams?

(d) In answering the above questions, which law have you used?

Miscellaneous Exercises | Q 35 | Page 97

The percentage composition of sodium phosphate as determined by analysis is 42.1% sodium, 18.9% phosphorus and 39% oxygen. Find the empirical formula of the compound?

Miscellaneous Exercises | Q 36 | Page 97

What volume of oxygen is required to burn completely a mixture of 22.4 dm3 of methane and 11.2 dm3 of hydrogen into carbon dioxide and steam?

CH4 + 2O2 → CO2 + 2H2O

2H2 + O2 → 2H2O

Miscellaneous Exercises | Q 37 | Page 97

The gases hydrogen, oxygen, carbon dioxide, sulphur dioxide, and chlorine are arranged in order of their increasing relative molecular masses. Given 8 g of each gas at S.T.P., which gas will contain the least number of molecules and which gas the most?

Miscellaneous Exercises | Q 38 | Page 97

10 g of a mixture of sodium chloride and anhydrous sodium sulphate is dissolved in water. An excess of barium chloride solution is added and 6.99 g of barium sulphate is precipitated according to the equation given below:

Na2SO4 + BaCl2 → BaSO4 + 2NaCl

Calculate the percentage of sodium sulphate in the original mixture.

Miscellaneous Exercises | Q 39 | Page 97

When heated, potassium permanganate decomposes according to the following equation :

$\ce{2KMnO4 -> \underset{\text{solid residue}}{K2MnO4 + MnO2} + O2}$

(a) Some potassium permanganate was heated in the test tube. After collecting one litre of oxygen at room temperature, it was found that the test tube had undergone a loss in mass of 1.32 g. If one litre of hydrogen under the same conditions of temperature and pressure has a mass of 0.0825 g, calculate the relative molecular mass of oxygen.

(b) Given that the molecular mass of potassium permanganate is 158. What volume of oxygen (measured at room temperature) would be obtained by the complete decomposition of 15.8 g of potassium permanganate? (Molar volume at room temperature is 24 litres)

Miscellaneous Exercises | Q 40.1 | Page 98

(a) A flask contains 3.2 g of sulphur dioxide. Calculate the following:

(i) The moles of sulphur dioxide present in the flask.

(ii) The number of molecules of sulphur dioxide present in the flask.

(iii) The volume occupied by 3.2 g of sulphur dioxide at S.T.P.

(S= 32, O= 16)

Miscellaneous Exercises | Q 40.2 | Page 98

An Experiment showed that in a lead chloride solution, 6.21 g of lead is combined with 4.26 g of chlorine. What is the empirical formula of this chlorine? (Pb = 207; Cl = 35.5)

Miscellaneous Exercises | Q 41 | Page 98

The volume of gases A, B, C, and D are in the ratio, 1: 2: 2: 4 under the same conditions of temperature and pressure.

(i) Which sample of gas contains the maximum number of molecules?

(ii) If the temperature and pressure of gas A are kept constant, then what will happen to the volume of A when the number of molecules is doubled?

(iii)If this ratio of gas volume refers to the reactants and products of a reaction, which gas law is being observed?

(iv)If the volume of A is actually 5.6 dm3 at S.T.P., calculate the number of molecules in the actual Volume of D at S.T.P. (Avogadro's number is 6 × 1023).

(v) Using your answer from (iv), state the mass of D if the gas is dinitrogen oxide (N2O)

Miscellaneous Exercises | Q 42 | Page 98

The equation given below relates the manufacture of sodium carbonate (molecular weight of Na2CO3 = 106).

1. NaCl+NH3+ CO2+ H2O→ NaHCO3+NH4Cl
2. 2NaHCO3→ Na2CO3+H2O + CO2

Equations (1) and (2) are based on the production of 21.2 g of sodium carbonate.

(a) What mass of sodium hydrogen carbonate must be heated to give 21.2 g of sodium carbonate?

(b) To produce the mass of sodium hydrogen carbonate calculate in (a), what volume of carbon dioxide, measured at S.T.P. would be required?

Miscellaneous Exercises | Q 43 | Page 98

A sample of ammonium nitrate when heated yields 8.96 litres of steam (measure at S.T.P.)

NH4NO3 → N2O + 2H2O

(i) What volume of dinitrogen oxide is produced at the same time as 8.96 litres of steam?

(ii) What mass of ammonium nitrate should be heated to produce 8.96 litres of steam? (Relative molecular mass of ammonium nitrate is 80)

(iii) Determine the percentage of oxygen in ammonium nitrate (O = 16).

Miscellaneous Exercises | Q 44 | Page 98

Given that the relative molecular mass of copper oxide is 80, what volume of ammonia (measured at STP) is required to completely reduce 120g of copper oxide? The equation for the reaction is :

$\ce{3CuO + 2NH3 → 3Cu + 3H2O + N2}$

Miscellaneous Exercises | Q 45 | Page 98

(a) Calculate the number of moles and the number of molecules present in 1.4 g of ethylene gas. What is the volume occupied by the same amount of ethylene?

(b) What is the vapour density of ethylene?

Miscellaneous Exercises | Q 46.1 | Page 98

Calculate the percentage of sodium in sodium aluminium fluoride (Na3AlF6) correct to the nearest whole number.

(F = 19; Na =23; Al = 27)

Miscellaneous Exercises | Q 46.2 | Page 98

560 ml of carbon monoxide is mixed with 500 ml of oxygen and ignited. The chemical equation for the reaction is as follows:

2CO + O2 → 2CO2

Calculate the volume of oxygen used and carbon dioxide formed in the above reaction.

## Chapter 5: Mole concept and Stoichiometry

Exercise 5AExercise 5BExercise 5CExercise 5DMiscellaneous Exercises

## Selina solutions for Concise Chemistry Class 10 ICSE chapter 5 - Mole concept and Stoichiometry

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