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.

611.

Consider the following equilibrium reaction: \(2AB_{{2}{(g)}} + B_{{2}{(g)}} \to 2AB_{{3}{(g)}}\). \(\Delta H= -X kJmol^{-1}\). The backward reaction will be favored by

A.

a decrease in pressure

B.

an increase in pressure

C.

a decrease in temperature

D.

an introduction of a positive catalyst

Correct answer is A

The equilibrium position is shifted to the left with a decrease in pressure in this system because the number of gaseous molecules on the right is less. (Le-Chatelier's principle).

612.

Ethene is produced from ethanol by

A.

decomposition

B.

hydrolysis

C.

ozonolysis

D.

dehydration

Correct answer is D

Ethene can be gotten from the dehydration of ethanol in the presence of excess  \(H_{2}SO_{4}\) or \(H_{3}PO_{4}\).

613.

Consider the following reaction equation: \(Br_{2} + 2KI \to 2KBr + I_{2}\). Bromine is acting as

A.

an oxidizing agent

B.

a reducing agent

C.

an acid

D.

a base

Correct answer is A

No explanation has been provided for this answer.

614.

An organic compound has the empirical formula \(CH_{2}\). If its molar mass is 42\(gmol^{-1}\), what is its molecular formula?  (C = 12.0, H = 1.0)

A.

\(C_{2}H_{4}\)

B.

\(C_{3}H_{4}\)

C.

\(C_{3}H_{6}\)

D.

\(C_{4}H_{8}\)

Correct answer is C

Given the molecular formula, \(CH_{2}\).

The empirical formula will be \((CH_{2})n\)= 42

\((12+(2\times1))n =42\)

⇒ \(14n =42\)

n = 3, hence the empirical formula is \(C_{3}H_{6}\)

615.

In which of the following compounds does hydrogen form ionic compounds?

A.

CH\(_{4}\)

B.

HCl

C.

NH\(_{3}\)

D.

NaH

Correct answer is D

The bonding between a non-metal and a metal is an ionic bonding. In metal hydrides, Hydrogen takes on the ionic charge of -1, hence forming an ionic bond with the metals.