Question

Assertion (A): Vapour density is the same thing as the density.

Reason (R): Molecular weight is twice the density.

Options

• If both A and R are true, and R is the correct explanation of A.

• If both A and R are true, but R is not the correct explanation of A.

• If A is true, but R is false.

• If both A and R are false.

Answer 1

If both A and R are false.

Explanation:

Assertion (A) is false because density is an absolute measurement of mass per unit volume (e.g., g/cm³), whereas vapour density is a relative, unitless value comparing the mass of a gas to the mass of an equal volume of hydrogen. Reason (R) is false because molecular weight is mathematically equal to twice the vapour density (Molecular Weight = 2 × Vapour Density), not the absolute density. Since both separate statements are scientifically incorrect.