Post Utme Chemistry Past Questions and Answers

Question 1041:

Polonium-210 undergoes alpha decay with a half-life of 138 days forming the stable isotope lead 206 . How much time would it take for the activity of a \(210 P _{0}\) sample to decrease to \(15 \%\) of initial value?

A. 138 days
B .143 days
B. 378 days
C. 172 days

Question 1042:

Ozonolysis of an unknown alkane gave propanone and methanol as final products, the unknown alkene is most likely ____________

A. 2-methylpropene
B. 2,3 dimethylbutene
C. Propene
D. 2-methylbut-2-ene

Question 1043:

Given the following organic compounds
i. Bromocthane
ii. But-2-yne
iii. But-1-yne
iv. Hydroxybenzene
Which one would you not expect to give any form of substitution reaction?

A. I
B. Ii
C. Iii
D. Iv

Question 1044:

Which of the following compounds will produce yellow/ orange precipitate with 2,4 dinitrophenylhydrazine? \(i\). \(CH -\) \({ }_{3} CH _{2} OH\) ii. \(CH _{3} CH _{2} CH ( OH )\) iii. \(CH _{3} CHO\) iv. \(CH _{3} COCH _{3}\)

A. I & ii
B. I, ii & iii
C. Iii & iv
D. I, ii, iii & iv

Question 1045:

Calculate the empirical formula of an oxide of tin if it is made up of \(11.3 \%\) of oxygen ____________
\(( Sn =119, O =16)\).

A. \(SnO _{2}\)
B. \(SnO\)
C. \(Sn _{2} O _{3}\)
D. \(Sn _{3} O _{2}\)