Cliffs AP Chemistry, 3rd Edition

68.A radioactive isotope has a half-life of

6.93 years and decays by beta emission.

Determine the approximate fraction of

the sample that is left undecayed at the

end of 11.5 years.

A. 1%

B. 5%

C. 30%

D. 75%

E. 99%

69.The solubility product constant at 25°C

for AgCl is 1.6 × 10 –10mol^2 ⋅L–2and

that for AgI is 8.0 × 10 –17mol^2 ⋅L–2.

Determine the equilibrium constant for

the reaction of silver chloride with

I–(aq).

A. 1.3 × 10 –26mol^2 ⋅L–2

B. 5.0 × 10 –7mol^2 ⋅L–2

C. 1.0 × 103 mol^2 ⋅L–2

D. 2.0 × 106 mol^2 ⋅L–2

E. 1.3 × 1016 mol^2 ⋅L–2

70.

Species Bond Energy (kcal/mole)

F–F 33

H–H 103

H–F 135

Calculate the value of ∆Hfor the

following reaction:

H 2 (g) + F 2 (g) →2 HF(g)

A. −406 kcal/mole

B. −320 kcal/mole

C. −271 kcal/mole

D. −134 kcal/mole

E. −1.00 kcal/mole

71. What happens to the velocities of
    different molecules as the temperature
    of a gas increases?

A. The velocities of all component

molecules increase equally.

B. The velocity range among different

molecules at higher temperatures is

smaller than that at lower

temperatures.

C. The effect on the velocities of the

molecules depends on whether the

pressure remains constant.

D. The velocity range among different

molecules at higher temperatures is

wider than the range at lower

temperatures.

E. None of these answer choices are

correct.

Part IV: AP Chemistry Practice Test