Physical Chemistry Preboard Exam

Which has the smallest value of speed?

• Root-mean-square

• Most probable

• Average

• All speeds are equal.

Refer to Figure 3.1. Which of the following is TRUE?

• T1 = T2

• T1 > T2

• T1 < T2

• Cannot be determined

The kinetic theory of gases is based on all of the following assumptions EXCEPT

• Gas consists of many particles of mass m, in continual motion.

• At high pressures, Gas particles are difficult to compress.

• Gas particles interact only by undergoing elastic collisions.

• None of the above

An ideal gas has twice the molar volume of the other at the same temperature. What is their pressure ratio?

• 1 : 2

• 1 : 4

• Cannot be determined

• 1 : 1/4

What is the molecular mass of a 4-gram gas if it occupies 11.2 L at 0°C and 0.25 atm?

• 16

• 20

• 48

• 32

Which of these three statements is TRUE?
I. The pressure exerted by each gas in a gas mixture (its partial pressure) is independent of the pressure exerted by all other gases present.
II. The total pressure exerted by a mixture of gases is the sum of the partial pressures of the component gases.
III. The amount of gas present in a mixture may be described by its partial pressure or its mole fraction.

• III. Only

• II. Only

• All these statements are true

• I. only

Which of the following effuses almost four times slower than hydrogen?

• helium

• Ethane

• chlorine

• water vapor

Which of the following is TRUE about the van der Waals 'a' and 'b'?

• 'b' corrects for the intermolecular interactions and 'a' for the included volume of the molecules

• 'b' corrects for the external pressure and 'a' for the internal pressure of the gas

• 'a' corrects for the intermolecular interactions and 'b' for the excluded volume of the molecules

• 'b' corrects for the free volume and 'a' for the intermolecular repulsion between molecules

At certain conditions, attractive forces among gas molecules exceed repulsive forces. Which of the following statements is NOT true?

• The fugacity coefficient is less than 1

• The compressibility factor is less than 1.

• The fugacity is greater than the pressure.

• The ideal volume is greater than the actual volume.

A mole of which gas has the smallest volume at 0°C and 1 atm?

• He

• CO2

• SO2

• Xe