A vessel of 120mL capacity contain a certain amount of gas at 35°c &1.2 bar pressure. The gas transferred to another vessal of volume 180mL at 35°c. What would be its pressure?

Since the temperature remains constant ($35 \text{ °C}$), we use Boyle's Law: $P_1V_1 = P_2V_2$.
Given:
$V_1 = 120 \text{ mL}$
$P_1 = 1.2 \text{ bar}$
$V_2 = 180 \text{ mL}$
$T_1 = T_2 = 35 \text{ °C}$ (constant temperature)
We need to find $P_2$.

The final pressure would be $\text{0.8 bar}$.