**(a):** Given: Temperature, T = 20°C = 273 + 20 = 293 K Pressure, P = 1.50 × 10^{5} Pa

Volume, V = 1.00 L = 0.001 m^{3}

**Required:** Number of moles, n of the gas

**Formula:** The general gas law is, PV = nRT

Put values in the formula,

** (b):** Pressure = atmospheric pressure = 1.01 × 10^{5} Pa

Volume = 2 × 0.001 = 0.002 m^{3}

**Required:** Temperature T

**Formula:** PV = nRt

Put values in the formula, 1.01 × 10^{5} × 0.002 = 6.61 × 10^{-2} × 8.314 × T