Question

Given below are few statements. Mark the statement which is not correct.

• A. Gram atomic mass of an element may be defined as the mass of Avogadro's number of atoms
• B. The molecular mass of a diatomic elementary gas is twice its atomic mass
• C. Gay Lussac's law of chemical combination is valid for all substances
• D. A pure compound has always a fixed proportion of masses of its constituents

Answer 1

The correct option is C Gay Lussac's law of chemical combination is valid for all substances

A: Gram atomic mass of an element is defined as the mass of one mole (or Avogadro's number) of atoms.

B: The molecular mass of a diatomic elementary gas is twice of its atomic mass. eg. mass of $O_2$ gas is $2\times 16=32g$

C: Gay Lussac's law of chemical combination is valid for a gaseous system only that are at similar temperature and pressure conditions.

D. A pure compound has always a fixed proportion of masses of its constituents: Law of definite proportion

option C is correct