Question

If pressure and temperature of an ideal gas are doubled and volume is halved, the number of molecules of gas.

• A. Become half
• B. Become two times
• C. Become four times
• D. Remain constant

Answer 1

The correct option is A Become half

Using Ideal gas equation, number of moles of gas $n=\frac{PV}{RT}$

New pressure $P^{\prime }=2P$

New temperature $T^{\prime }=2T$

New volume $V^{\prime }=V/2$

Thus number of moles of gas $n^{\prime }=\frac{P^{\prime }{V}^{\prime }}{R{T}^{\prime }}$

$\therefore$ $n^{\prime }=\frac{\left(2P\right)\left(V/2\right)}{R\left(2T\right)}=\frac{n}{2}$

So, option A is correct.