Gas at pressure P, temperature T, and volume V is filled in jar A. Another jar B is filled with gas having parameters \(2P\), \(\frac{V}{4}\), \(2T\). The ratio of number of molecules of jar B to those of jar A is
Step 1: Use moles:
$n = \frac{PV}{RT}$. Compare $n_B$ and $n_A$.
Step 2: Numerator:
The product $PV$ changes by $2 \times \frac14 = \frac12$.
Step 3: Denominator:
The temperature doubles, giving another factor $\frac12$. Total factor $\frac12 \times \frac12 = \frac14$, so $N_B : N_A = 1 : 4$.
Final Answer:
The ratio is 1:4, option (B).
\[ \boxed{1:4} \]