# NCERT solutions for Chemistry Part 1 and 2 Class 11 chapter 1 - Some Basic Concepts of Chemistry [Latest edition]

## Chapter 1: Some Basic Concepts of Chemistry

EXERCISES
EXERCISES [Pages 25 - 28]

### NCERT solutions for Chemistry Part 1 and 2 Class 11 Chapter 1 Some Basic Concepts of ChemistryEXERCISES [Pages 25 - 28]

EXERCISES | Q 1.1 - (i) | Page 25

Calculate the molar mass of the following:

H2O

EXERCISES | Q 1.1 - (ii) | Page 25

Calculate the molar mass of the following:

CO2

EXERCISES | Q 1.1 - (iii) | Page 25

Calculate the molar mass of the following:

CH4

EXERCISES | Q 1.2 | Page 25

Calculate the mass percent of different elements present in sodium sulphate (Na2SO4).

EXERCISES | Q 1.3 | Page 25

Determine the empirical formula of an oxide of iron, which has 69.9% iron and 30.1% dioxygen by mass.

EXERCISES | Q 1.4 - (i) | Page 25

Calculate the amount of carbon dioxide that could be produced when 1 mole of carbon is burnt in air.

EXERCISES | Q 1.4 - (ii) | Page 25

Calculate the amount of carbon dioxide that could be produced when 1 mole of carbon is burnt in 16 g of dioxygen.

EXERCISES | Q 1.4 - (iii) | Page 25

Calculate the amount of carbon dioxide that could be produced when 2 moles of carbon are burnt in 16 g of dioxygen.

EXERCISES | Q 1.5 | Page 25

Calculate the mass of sodium acetate (CH3COONa) required to make 500 mL of 0.375 molar aqueous solution. Molar mass of sodium acetate is 82.0245 g mol–1.

EXERCISES | Q 1.6 | Page 26

Calculate the concentration of nitric acid in moles per litre in a sample which has a density, 1.41 g mL–1and the mass per cent of nitric acid in it being 69%.

EXERCISES | Q 1.7 | Page 26

How much copper can be obtained from 100 g of copper sulphate (CuSO4)?

EXERCISES | Q 1.8 | Page 26

Determine the molecular formula of an oxide of iron in which the mass percent of iron and oxygen are 69.9 and 30.1 respectively. Given that the molar mass of the oxide is 159.69 g mol–1.

EXERCISES | Q 1.9 | Page 26

Calculate the atomic mass (average) of chlorine using the following data :-

 % Natural Abundance Molar Mass 35Cl 75.77 34.9689 37Cl 24.23 36.9659
EXERCISES | Q 1.10 - (i) | Page 26

In three moles of ethane (C2H6), calculate the Number of moles of carbon atoms.

EXERCISES | Q 1.10 - (ii) | Page 26

In three moles of ethane (C2H6), calculate the Number of moles of hydrogen atoms.

EXERCISES | Q 1.10 - (iii) | Page 26

In three moles of ethane (C2H6), calculate the Number of molecules of ethane.

EXERCISES | Q 1.11 | Page 26

What is the concentration of sugar (C12H22O11) in mol L–1 if its 20 g are dissolved in enough water to make a final volume up to 2 L?

EXERCISES | Q 1.12 | Page 26

If the density of methanol is 0.793 kg L–1, what is its volume needed for making 2.5 L of its 0.25 M solution?

EXERCISES | Q 1.13 | Page 26

Pressure is determined as force per unit area of the surface. The SI unit of pressure, Pascal is as shown below:-
1Pa = 1N m–2
If mass of air at sea level is 1034 g cm–2, calculate the pressure in Pascal.

EXERCISES | Q 1.14 | Page 26

What is the SI unit of mass? How is it defined?

EXERCISES | Q 1.15 | Page 26

Match the following prefixes with their multiples:-

 Prefixes Multiples (i) micro 106 (ii) deca 109 (iii) mega 10-6 (iv) giga 10-15 (v) femto 10
EXERCISES | Q 1.16 | Page 26

Describe what is meant by significant figures.

EXERCISES | Q 1.17 | Page 26

A sample of drinking water was found to be severely contaminated with chloroform, CHCl3, supposed to be carcinogenic in nature. The level of contamination was 15 ppm (by mass).

1. Express this in percent by mass.
2. Determine the molality of chloroform in the water sample.
EXERCISES | Q 1.18 - (i) | Page 26

Express the following in the scientific notation:

0.0048

EXERCISES | Q 1.18 - (ii) | Page 26

Express the following in the scientific notation:

234,000

EXERCISES | Q 1.18 - (iii) | Page 26

Express the following in the scientific notation:

8008

EXERCISES | Q 1.18 - (iv) | Page 26

Express the following in the scientific notation:

500.0

EXERCISES | Q 1.18 - (v) | Page 26

Express the following in the scientific notation:

6.0012

EXERCISES | Q 1.19 - (i) | Page 26

How many significant figures are present in the 0.0025?

EXERCISES | Q 1.19 - (ii) | Page 26

How many significant figures are present in the 208?

EXERCISES | Q 1.19 - (iii) | Page 26

How many significant figures are present in the 5005?

EXERCISES | Q 1.19 - (iv) | Page 27

How many significant figures are present in the 126,000?

EXERCISES | Q 1.19 - (v) | Page 27

How many significant figures are present in the 500.0?

EXERCISES | Q 1.19 - (vi) | Page 27

How many significant figures are present in the 2.0034?

EXERCISES | Q 1.20 - (i) | Page 27

Round up the following upto three significant figures:

34.216

EXERCISES | Q 1.20 - (ii) | Page 27

Round up the following upto three significant figures:

10.4107

EXERCISES | Q 1.20 - (iii) | Page 27

Round up the following upto three significant figures:

0.04597

EXERCISES | Q 1.20 - (iv) | Page 27

Round up the following upto three significant figures:

2808

EXERCISES | Q 1.21 | Page 27

The following data are obtained when dinitrogen and dioxygen react together to form different compounds:-

 Mass of dinitrogen Mass of dioxygen (i) 14 g 16 g (ii) 14 g 32 g (iii) 28 g 32 g (iv) 28 g 80 g

(a) Which law of chemical combination is obeyed by the above experimental data?Give its statement.

(b) Fill in the blanks in the following conversions:

(i) 1 km = ______ mm = ______ pm

(ii) 1 mg = ______ kg = ______ ng

(iii) 1 mL = ______ L = _______ dm3

EXERCISES | Q 1.22 | Page 27

If the speed of light is 3.0 ×108 m s-1, calculate the distance covered by light in 2.00 ns.

EXERCISES | Q 1.23 - (i) | Page 27

In a reaction, $\ce{A + B2 -> AB2}$

Identify the limiting reagent, if any, in the following reaction mixture.

300 atoms of A + 200 molecules of B

EXERCISES | Q 1.23 - (ii) | Page 27

In a reaction, $\ce{A + B2 -> AB2}$

Identify the limiting reagent, if any, in the following reaction mixture.

2 mol A + 3 mol B

EXERCISES | Q 1.23 - (iii) | Page 27

In a reaction, $\ce{A + B2 -> AB2}$

Identify the limiting reagent, if any, in the following reaction mixture.

100 atoms of A + 100 molecules of B

EXERCISES | Q 1.23 - (iv) | Page 27

In a reaction, $\ce{A + B2 -> AB2}$

Identify the limiting reagent, if any, in the following reaction mixture.

5 mol A + 2.5 mol B

EXERCISES | Q 1.23 - (v) | Page 27

In a reaction, $\ce{A + B2 -> AB2}$

Identify the limiting reagent, if any, in the following reaction mixture.

2.5 mol A + 5 mol B

EXERCISES | Q 1.24 | Page 27

Dinitrogen and dihydrogen react with each other to produce ammonia according to the following chemical equation:

$\ce{N2 (g) + 3H2 (g) → 2NH3 (g)}$

(i) Calculate the mass of ammonia produced if 2.00 × 103 g dinitrogen reacts with 1.00 × 103 g of dihydrogen.

(ii) Will any of the two reactants remain unreacted?

(iii) If yes, which one and what would be its mass?

EXERCISES | Q 1.25 | Page 27

How are 0.50 mol Na2CO3 and 0.50 M Na2CO3 different?

EXERCISES | Q 1.26 | Page 27

If 10 volumes of dihydrogen gas reacts with five volumes of dioxygen gas, how many volumes of water vapour would be produced?

EXERCISES | Q 1.27 - (i) | Page 27

Convert the following into basic units:

28.7 pm

EXERCISES | Q 1.27 - (ii) | Page 27

Convert the following into basic units:

15.15 pm

EXERCISES | Q 1.27 - (iii) | Page 27

Convert the following into basic units:

25365 mg

EXERCISES | Q 1.28 | Page 28

Which one of the following will have largest number of atoms?

• 1 g Au (s)

• 1 g Na (s)

• 1 g Li (s)

• 1 g of Cl2(g)

EXERCISES | Q 1.29 | Page 28

Calculate the molarity of a solution of ethanol in water in which the mole fraction of ethanol is 0.040 (assume the density of water to be one).

EXERCISES | Q 1.30 | Page 28

What will be the mass of one 12C atom in g?

EXERCISES | Q 1.31 - (i) | Page 28

How many significant figures should be present in the answer of the following calculation:-

(0.02856 xx 298.15 xx 0.112)/0.5785

EXERCISES | Q 1.31 - (ii) | Page 28

How many significant figures should be present in the answer of the following calculation?

5 × 5.364

EXERCISES | Q 1.31 - (iii) | Page 28

How many significant figures should be present in the answer of the following calculation?

0.0125 + 0.7864 + 0.0215

EXERCISES | Q 1.32 | Page 28

Use the data given in the following table to calculate the molar mass of naturally occurring argon isotopes:-

 Isotope Isotopic molar mass Abundance 36Ar 35.96755 gmol-1 0.337% 38Ar 37.96272 gmol-1 0.063% 40Ar 39.9624 gmol-1 99.600%
EXERCISES | Q 1.33 - (i) | Page 28

Calculate the number of atoms of the 52 moles of Ar.

EXERCISES | Q 1.33 - (ii) | Page 28

Calculate the number of atoms of the 52 u of He.

EXERCISES | Q 1.33 - (iii) | Page 28

Calculate the number of atoms of the 52 g of He.

EXERCISES | Q 1.34 | Page 28

A welding fuel gas contains carbon and hydrogen only. Burning a small sample of it in oxygen gives 3.38 g carbon dioxide, 0.690 g of water and no other products. A volume of 10.0 L (measured at STP) of this welding gas is found to weigh 11.6 g. Calculate

1. empirical formula,
2. molar mass of the gas, and
3. molecular formula.
EXERCISES | Q 1.35 | Page 28

Calcium carbonate reacts with aqueous HCl to give CaCl2 and CO2 according to the reaction,

$\ce{CaCO_{3(s)} + 2 HCl_{(aq)} → CaCl_{2(aq)} + CO_{2(g)} + H2O_{(l)}}$

What mass of CaCO3 is required to react completely with 25 mL of 0.75 M HCl?

EXERCISES | Q 1.36 | Page 28

Chlorine is prepared in the laboratory by treating manganese dioxide (MnO2) with aqueous hydrochloric acid according to the reaction

$\ce{4HCl_{(aq)} + MnO_{2(s)} → 2H2O_{(l)} + MnCl_{2(aq)} + Cl_{2(g)}}$

How many grams of HCl react with 5.0 g of manganese dioxide?

EXERCISES

## NCERT solutions for Chemistry Part 1 and 2 Class 11 chapter 1 - Some Basic Concepts of Chemistry

NCERT solutions for Chemistry Part 1 and 2 Class 11 chapter 1 (Some Basic Concepts of Chemistry) include all questions with solution and detail explanation. This will clear students doubts about any question and improve application skills while preparing for board exams. The detailed, step-by-step solutions will help you understand the concepts better and clear your confusions, if any. Shaalaa.com has the CBSE Chemistry Part 1 and 2 Class 11 solutions in a manner that help students grasp basic concepts better and faster.

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Concepts covered in Chemistry Part 1 and 2 Class 11 chapter 1 Some Basic Concepts of Chemistry are Importance of Chemistry, Historical Approach to Particulate Nature of Matter, Nature of Matter, The International System of Units (Si), Mass and Weight, Scientific Notation, Dimensional Analysis, Law of Conservation of Mass, Law of Definite Proportions, Law of Multiple Proportions, Gay Lussac’s Law of Gaseous Volumes, Avogadro Law, Atomic Mass, Average Atomic Mass, Molecular Mass, Formula Mass, Mole Concept and Molar Masses, Percentage Composition, Stoichiometry and Stoichiometric Calculations - Introduction, Limiting Reagent, Stoichiometry and Stoichiometric Calculations - Reactions in Solutions, Dalton's Atomic Theory, Significant Figures, Introduction of Some Basic Concepts of Chemistry.

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