Post Utme Chemistry Past Questions and Answers

Question 941:

A chloroform solution of pure organic compound was spotted at a distance \(0.80 cm\) from the base of a \(20 cm\) long chromatoplate. If the compound has the \(R _{ f }\) value of \(0.50\) and moves half way up the \(20 cm\) long plate, what is the distance of the solvent front from the top of the plate upon elution?

A. \(0.80 cm\)
B. \(1.0 cm\)
C. \(1.2 cm\)
D. \(1.4 cm\)

Question 942:

Platinum electrodes are dipped into copper sulphate solution in a voltameter. The solution left after electrolysis is ____________

A. Clear
B. Blue
C. Purple
D. Pale green

Question 943:

The equilibrium constant, \(K _{ C }\) for the reaction, \(NO _{( g )}+\) \(1 / 2 O _{2(\beta)} \rightarrow NO _{2( g )}\), is \(35.2\). What is the value of \(K _{ C }\) for the reaction, \(NO _{2( g )} \rightarrow NO _{(\varepsilon)}+1 / 2 O _{2(\varepsilon)}\) ?

A. \(35.2\)
B. \(17.6 \)
C. \(2.84 \times 10^{-2}\)
D. \(1.24 \times 10^{3}\)

Question 944:

\(CH _{3} CH _{2} Cl + NaOH \rightarrow CH _{3} CH _{2} OH + NaCl\).
The above reaction is best described will proceed to form the products by a process known as ____________

A. Nucleophilic addition
B. Nucleophilic substitution
C. Electrophilic addition
D. Electrophilic substitution

Question 945:

What quantity of current is required to deposit \(2.4 g\) of copper in a period of 750 seconds during an electrolytic deposition process?
\(\left[ Cu =64,1 F =96500 coulmol ^{-1}\right] \)

A. \(9.65\) A
B. \(10.81\) A
C. \(12.33\) A
D. \(15.54 A\)