4. Which of the following equations represents the correct form of Vander Waal's equation at very low pressure? A) PV=RTa/V B) PV=nRT C) P(Vmb)=RT D) P(Vb)=RT E) (P+an2/V2)(Vnb)=nRT 5. Most ideal gas at room temperature is: A) CO2 B) NH3 C) SO2 D) N2 E) All behave as ideal gases 6. The value of compressibility factor (PVRT ratio) for an ideal gas is equal to: A) 1 B) 1.5 C) 2 D) 2.5 E) 4 7. A real gas obeying Vander Waal's equation: (P+V2an2)(Vnb)=nRT will resemble ideal gas if: A) Both ' a ' and ' b ' are large B) Both ' a ' and ' b ' are small C) ' a ' is small and ' b ' is large D) ' a ' is large and ' b ' is small E) None of the above