Chemistry questions and answers

Chemistry Questions and Answers

Learn more about the properties, composition, and structure of substances (elements and compounds) with these Chemistry questions and answers. This Test can be used by students preparing for Chemistry in JAMB, WAEC, NECO or Post UTME.

531.

Classification of alkanols is based on the 

A.

number of carbon atoms present in the compound

B.

molecular mass of the compound

C.

molecular formula of the compound

D.

number of alkyl groups bonded to the carbon having the hydroxyl group

Correct answer is D

Alkanols can be classified as primary, secondary or tertiary, according to the number of alkyl groups attached to the carbon which bears the -OH group. 

532.

Calculate the mass of copper deposited if a current of 0.45A flows through \(CuSO_{4}\) solution for 1hour 15mins.   [Cu=64.0, S= 32.0, O =16.0, 1F= 96500C]

A.

6.40g

B.

0.67g

C.

0.64g

D.

0.45g

Correct answer is B

\(Cu^{2+} + 2e^{-}  \to  Cu_{(s)}\)

\( 2 \times 96500C = 193000C  deposits 64g of Cu\)

\(M \propto It\)

\(Q = It = 0.45A \times 1hr15mins\)

= \( 0.45 \times 75 \times 60\) [converting the time to seconds]

Quantity of electricity passed = 2025C

\(193000C \to 64g Cu\)

\(1C \to \frac{64}{193000}\)

\(2025C \to \frac{64}{193000} \times 2025\)

\(= 0.6715g  \approxeq  0.67g\)

533.

Which of the following factors characterize members of the same homologous series?

A.

The chemical property change gradually throughout the series

B.

physical properties of members are similar

C.

They have the same molecular formular

D.

Successive members undergo changes in molecular formula by \(CH_{2}\)

Correct answer is D

The difference between every successive member of the same homologous series is always \(CH_{2}\) eg methane is \(CH_{4}\) and ethane is \(C_{2}H_{6}\), difference being \(CH_{2}\).

534.

Consider the following reaction equation: \(2NO_{(g)} + O_{{2}{(g)}} \to 2NO_{{2}{(g)}}\). What is the change in the oxidation number of nitrogen?

A.

+2 to 0

B.

+2 to -2

C.

+2 to +4

D.

+4 to +2

Correct answer is C

In NO, the oxidation number for nitrogen is N - 2 = 0

⇒ N = +2

In \(NO_{2}\), we have N - (2x2) =0

N - 4 =0

N =+4

535.

The common feature of reactions at the anode is that

A.

electrons are consumed

B.

ions are reduced

C.

oxidation is involved

D.

the electrode dissolves

Correct answer is C

In both the electrochemical cell and the electrolytic cell, at the anode, oxidation is involved.