Question

$A,B$ and $C$ gases taken in a volume ratio of $3:2:4$ contains atoms in the ratio of $1:2:8/3$. The gases having minimum and maximum atomicity are respectively:

• A. $C$ and $B$
• B. $A$ and $C$
• C. $A$ and $B$
• D. $B$ and $C$ have same atomicity

Answer 1

Answer: (C)

$A$ and $B$

Ratio of volumes for gases $A:B:C=3:2:4$

Since, volume of a gas is directly proportional to moles at a given set of conditions, ratio of moles of gases $=3:2:4$

Ratio of atoms $=1:2:8/3$

$3moles$ of gas $A$ contain atoms $=x$

$1molecule$ of gas has atoms $=\frac{x}{3N_A}$

Atomicity $=\frac{x}{3N_A}$

$2moles$ of gas $B$ contain atoms $=2x$

$1molecule$ of gas has atoms $=\frac{2x}{2N_A}$

Atomicity $=\frac{x}{N_A}$

$4moles$ of gas $C$ contain atoms $=\frac{8}{3}x$

$1molecule$ of gas has atoms $=\frac{\frac{8x}{3}}{4N_A}$

Atomicity $=\frac{2x}{3N_A}$

Therefore gas $A$ has minimum atomicity while gas $B$ has maximum atomicity.