(English Medium) ICSE Class 10 - CISCE Important Questions

A ______ coloured precipitate is formed when ammonium hydroxide is added to a solution of ferrous chloride.

Propane burns in air according to the following equation: 

C₃H₈ + 5O₂ → 3CO₂ + 4H₂O

What volume of propane is consumed on using 1000 cm³ of air, considering only 20% of air contains oxygen?

State Gay-Lussac's law of combining volumes.

Calculate the percentage of water of crystallization in CuSO₄.5H₂O

(H = 1, O = 16, S = 32, Cu = 64)

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

1) Find the number of moles of hydrogen present.

2) What weight of CO2 can the cylinder hold under similar conditions of temperature and pressure? (H = 1, C = 12, O = 16)

3) If the number of molecules of hydrogen in the cylinder is X, calculate the number of CO₂ molecules in the cylinder under the same conditions of temperature and pressure.

4) State the law that helped you to arrive at the above result.

Choose the correct answer from the options given below:

The ratio between the number of molecules in 2g of hydrogen and 32g of oxygen is:

[Given that H = 1, O = 16]

Give balanced chemical equations for the following conversions A, B, and C:

The percentage composition of a gas is Nitrogen 82.35%, Hydrogen 17.64%. Find the empirical formula of the gas.  [N = 14, H = 1]

Aluminium carbide reacts with water according to the following equation :

`Al_4C_3 + 12H_2O-> 4Al(OH)_3 + 3CH_4`

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

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

[Relatively molecular weight of `Al_4Cl_3 = 144; Al(OH)_3 = 78]`

Calculate the number of moles in 12g of oxygen gas.

Define the term.

Molar volume

The vapour density of CH₃OH is ______. (At. Wt. C = 12, H = 1, O = 16)

A compound of X and Y has the empirical formula XY₂. Its vapor density is equal to its empirical formula weight. Determine its molecular formula.

Identify the term or substance based on the descriptions given below:

The property by virtue of which the compound has the same molecular formula but different structural formulae.

A gaseous hydrocarbon contains 82.76% of carbon. Given that its vapor density is 29, find its molecular formula. [C = 12, H = 11]

If the empirical formula of a compound is CH and it has a vapor density of 13, find the molecular formula of the compound.

Consider the following reaction and based on the reaction answer the questions that follow:

Calculate:

1) the quantity in moles of (NH₄)₂Cr₂O₇ if 63gm of(NH₄)₂Cr₂O₇ is heated.

2) the quantity in moles of nitrogen formed.

3) the volume in liters or dm3 of N2 evolved at S.T.P.

4) the mass in grams of Cr2O3 formed at the same time

(Atomic masses: H=1, Cr= 52, N=14]

A compound made up of two elements X and Y has an empirical formula X₂Y. If the atomic weight of X is 10 and that of Y is 5 and the compound ha a vapor density 25, find its molecular formula.

Ethane burns in oxygen to form CO₂ and H₂O according to the equation:

`2C_2H_6+7O_2 -> 4CO_2 + 6H_2O`

If 1250 cc of oxygen is burnt with 300 cc of ethane.

Calculate:

1) the volume of `CO_2` formed

2) the volume of unused `O_2`

 Give the appropriate term defined by the statements given below : 
The formula that represents the simplest ratio of the various elements present in one molecule of the compound.