Post Utme Chemistry Past Questions and Answers

Question 681:

Which of the following gasses will diffuse fastest when passed through a porous plug?
\((\mathrm{H}=1, \mathrm{C}=12, \mathrm{~N}=14, \mathrm{O}=16)\)

A. Propane
B. Oxygen
C. Methane
D. Ammonia

Question 682:

Which of the following will have its mass increased when healed in air?

A. Hellum
B. Magneslum
C. Copper pyrites
D. Glass

Question 683:

What is the temperature of a glven mass of a gas Initlally \(0^{\circ} \mathrm{C}\) and \(9 \mathrm{~atm}\), If the pressure is reduced to 3 atmosphere at constant volume?

A. \(91 \mathrm{k}\)
B. \(182 \mathrm{k}\)
C. 273
D. \(819 k\)

Question 684:

65 . [image]
In the dlagram above, the mixture of the solids \(P\) and \(Q\) can be separated

A. Distillation
B. Fractional distillation
C. Crystallization
D. Fractional crystallization

Question 685:

\(\mathrm{Mg}(\) o \()+2 \mathrm{HCl}_{\text {(a) })}
ightarrow \mathrm{MgCl}_{2(1)}+\mathrm{N}_{2(9)}\). From the equation above, the mass of magnesium required to react with \(250 \mathrm{~cm}^{2}\) of \(\mathrm{MHCl}\) is ____________
\((M-27, C l=35.5)\)

A. \(0.39\)
B. \(1.5 \mathrm{~g}\)
C. \(2.4\)
D. \(3.0\)