Chemistry MCQ

A chemist is decomposing calcium carbonate to produce calcium oxide and carbon dioxide according to the equation: CaCO₃ → CaO + CO₂
The chemist starts with 200 grams of CaCO₃ (molar mass = 100 g/mol).
Assertion (A): The mass of CaO produced will be 112 grams (molar mass of (CaO = 56) g/mol).
Reason (R): The molar ratio of CaCO₃ to CaO in the balanced equation is 1:1.
Choose the correct option:

Assertion (A): The empirical formula and molecular formula of a compound can be identical.
Reason (R): The molecular formula of a compound is always a multiple of its empirical formula.

Assertion (A): If the temperature of a gas is tripled, while keeping the volume constant, the pressure of the gas will also triple.
Reason (R): According to Gay Lussac's Law, the pressure of a gas is directly proportional to its absolute temperature when the volume is constant.

C₃H₄(g) + 4O₂(g) → 3CO₂(g) + 2H₂O
Propyne gas burns as is shown in equation above. If 5.6 dm³ of propyne at S.T.P. burns completely the volume of oxygen required at S.T.P. is:

A gaseous hydrocarbon of vapour density 29, contains 82.76% of carbon and rest hydrogen. [C = 12; H = 1]
The molecular formula of the gaseous hydrocarbon is:

A gaseous hydrocarbon has V.D. 29 and contains 17.24% of hydrogen.
The molecular formula of hydrocarbon is:

The % age of oxygen in aluminium sulphate [Al₂(SO₄)₃] is: [Al = 27; S = 32; O = 16]

The percentage of pure iron in 10 kg of iron (III) oxide [Fe₂O₃] of 80% purity is:
[Fe = 56; O = 16]

If the relative molecular mass of the above compound is 168, then its molecular formula is:

A compound has following % age composition by mass:
carbon 14.4%; hydrogen 1.2% and chlorine 84.5%. If atomic masses of C = 12, H = 1 and Cl = 35.5, then empirical formula of compound is:

NH₄NO₃ on heating decomposes as under:
NH₄NO₃ → N₂O(g) + 2H₂O
If 5.6 dm³ of N₂O is valued at S.T.P, the weight of NH₄NO₃ required is: [N = 14; O = 16]

Whenever the gases react under similar conditions of temperature and pressure they do so in volumes, which bear a simple ratio of each other, and the products if gaseous. The above law was stated by:

N₂(g) + O₂(g) → 2NO(g)
Nitrogen and oxygen react as illustrated by the equation above to form 1400 ml of nitric oxide gas. The volume of oxygen which takes part in reaction, such that temperature and pressure of all gases remain same is: