Year : 
2014
Title : 
Chemistry
Exam : 
WASSCE/WAEC MAY/JUNE

Paper 1 | Objectives

11 - 20 of 45 Questions

# Question Ans
11.

NH4- is formed from NH3 and H- by

A. covalent bonding

B. dative bonding

C. hydrogen bonding

D. ionic bonding

B
12.

How many lone pair (s) of electrons is present in HF?

A. o

B. 1

C. 2

D. 3

D
13.

An aqueous solution of Na2CO3 is

A. acidic

B. alkaline

C. amphoteric

D. neutral

B
14.

A gaseous mixture contains 0,256 g of hydrogen and 2.00 g of oxygen. The mole ration of hydrogen to oxygen in the mixture is (H=1.00; O=16,0)

A. 1:1

B. 2:1

C. 1:4

D. 8:1

Detailed Solution

Mole = \(\frac{Mass}{Molar Mas}\) : \(\frac{Mass}{Molar Mass}\)
\(\frac{0.256}{2}\) : \(\frac{2}{32}
0. 128 : 0.0625
\(\frac{0.128}{0.0625}\) : \(\frac{0.0625}{0.0625}\)
2 : 1
15.

The oxidation number of sulphur in Fe2(SO4)3 is

A. +2.

B. +3

C. +4.

D. +6.

Detailed Solution

Fe2(SO4)3 = 0
(+3 x 2) 9 3x + (-2 x 4 x 3) = 0
+6 + 3x -24 = 0
+3x - 18 = 0
3 x = 18
x = 18/3 = +6
16.

If 0.20 mol dm-3 NaOH(aq) was evaporated to yield 5.0g of solid NaOH, calculate the volume of NaOH (aq) used. (Na = 23.0,O = 16:0; H = 1.00)

A. 600cm-3

B. 625cm3

C. 10003

D. 1600 cm 3

Detailed Solution

Mole = 5/40 = 0.125 mole
:. 0.2 mole NaOH dissolved in 1000 cm3
0.125 mole NaOH dissolved in xcm3
xcm3 = \(\frac{0.215 x 1000}{0.2}\)
= 625cm3
17.

The mass of 800cm3 of gas Q at s.t.p. is 1.0g. What is the molar mass of Q? [Avogadros constant = 22.4dm3 mol-1`]

A. 18.0 gmol-1

B. 22,4gmol-1

C. 28.0gmol-1

D. 36.0 gmol-1

Detailed Solution

Imole Q occupies 22400 cm3
x mole occupies 800 cm3
x = \(\frac{800 x 1}{22400}\)
= 0.036mol
Molar mass = Mass ÷ Mole
= 1 ÷ 0.036
Molar mass ≈ 28 g/mol
18.

Which of the following statements about a chemical system in equilibrium is correct/ The

A. reaction is irreversible

B. reaction goes to completion

C. equilibrium is re-established when a stress is applied

D. equilibrium position is affected by catalyst

C
19.

Which of the following relationships correctly expresses the Boyle's law?

A. P \(\alpha\) V at constant T

B. V \(\alpha\) T at constant P

C. P \(\alpha\) \(\frac{1}{V}\) at constant T

D. V \(\alpha\) \(\frac{1}{T}\) at constant P

C
20.

The vapour pressure of a given volume of liquid increase when the

A. liquid becomes saturated with a salt

B. Volume of the liquid increases

C. temperature of the liquid falls

D. temperature of the Liquid rises

D
11.

NH4- is formed from NH3 and H- by

A. covalent bonding

B. dative bonding

C. hydrogen bonding

D. ionic bonding

B
12.

How many lone pair (s) of electrons is present in HF?

A. o

B. 1

C. 2

D. 3

D
13.

An aqueous solution of Na2CO3 is

A. acidic

B. alkaline

C. amphoteric

D. neutral

B
14.

A gaseous mixture contains 0,256 g of hydrogen and 2.00 g of oxygen. The mole ration of hydrogen to oxygen in the mixture is (H=1.00; O=16,0)

A. 1:1

B. 2:1

C. 1:4

D. 8:1

Detailed Solution

Mole = \(\frac{Mass}{Molar Mas}\) : \(\frac{Mass}{Molar Mass}\)
\(\frac{0.256}{2}\) : \(\frac{2}{32}
0. 128 : 0.0625
\(\frac{0.128}{0.0625}\) : \(\frac{0.0625}{0.0625}\)
2 : 1
15.

The oxidation number of sulphur in Fe2(SO4)3 is

A. +2.

B. +3

C. +4.

D. +6.

Detailed Solution

Fe2(SO4)3 = 0
(+3 x 2) 9 3x + (-2 x 4 x 3) = 0
+6 + 3x -24 = 0
+3x - 18 = 0
3 x = 18
x = 18/3 = +6
16.

If 0.20 mol dm-3 NaOH(aq) was evaporated to yield 5.0g of solid NaOH, calculate the volume of NaOH (aq) used. (Na = 23.0,O = 16:0; H = 1.00)

A. 600cm-3

B. 625cm3

C. 10003

D. 1600 cm 3

Detailed Solution

Mole = 5/40 = 0.125 mole
:. 0.2 mole NaOH dissolved in 1000 cm3
0.125 mole NaOH dissolved in xcm3
xcm3 = \(\frac{0.215 x 1000}{0.2}\)
= 625cm3
17.

The mass of 800cm3 of gas Q at s.t.p. is 1.0g. What is the molar mass of Q? [Avogadros constant = 22.4dm3 mol-1`]

A. 18.0 gmol-1

B. 22,4gmol-1

C. 28.0gmol-1

D. 36.0 gmol-1

Detailed Solution

Imole Q occupies 22400 cm3
x mole occupies 800 cm3
x = \(\frac{800 x 1}{22400}\)
= 0.036mol
Molar mass = Mass ÷ Mole
= 1 ÷ 0.036
Molar mass ≈ 28 g/mol
18.

Which of the following statements about a chemical system in equilibrium is correct/ The

A. reaction is irreversible

B. reaction goes to completion

C. equilibrium is re-established when a stress is applied

D. equilibrium position is affected by catalyst

C
19.

Which of the following relationships correctly expresses the Boyle's law?

A. P \(\alpha\) V at constant T

B. V \(\alpha\) T at constant P

C. P \(\alpha\) \(\frac{1}{V}\) at constant T

D. V \(\alpha\) \(\frac{1}{T}\) at constant P

C
20.

The vapour pressure of a given volume of liquid increase when the

A. liquid becomes saturated with a salt

B. Volume of the liquid increases

C. temperature of the liquid falls

D. temperature of the Liquid rises

D