A rigid 1.50 L container holds an ideal gas. Two measurements on a P–T graph give (T₁ = 250 K, P₁ = 102 kPa) and (T₂ = 350 K, P₂ = 143 kPa). Using only these data, calculate the number of moles of gas in the container. (Take R = 8.31 kPa·L mol⁻¹ K⁻¹.)