Let's assume that the given gas has an ideal gas behavior. So we can use ideal gas law,
PV = nRT
Where P is the pressure of the gas (Pa), V is the volume of the gas (m³), n is the number of moles of gas (mol), R is the universal gas constant (8.314 J mol⁻¹ K⁻¹) and T is temperature in Kelvin (K).
P = ?
V = 30.0 L = 30.0 x 10⁻³ m³
n = 5.00 mol
R = 8.314 J mol⁻¹ K⁻¹
T = 25.0 + 273 K = 298 K
By applying the equation,
P x 30.0 x 10⁻³ m³ = 5.00 mol x 8.314 J mol⁻¹ K⁻¹ x 298 K
P = 412928.67 Pa
P = 4.13 x 10⁵ Pa
Hence, the pressure of the gas is 4.13 x 10⁵ Pa