Year : 
2018
Title : 
Chemistry
Exam : 
JAMB Exam

Paper 1 | Objectives

41 - 50 of 87 Questions

# Question Ans
41.

When air which contains the gases Oxygen, nitrogen, carbondioxide, water vapour and the rare gases, is passed through alkaline pyrogallol and then over quicklime, the only gases left are;

A. nitrogen and carbondioxide

B. the rare gases

C. nitrogen and oxygen

D. nitrogen and the rare gases

Detailed Solution

The quick-lime is a drying agent that can dry most gases except ammonia. Hence it removes the water vapour. Quick-lime which is calcium oxide reacts with the carbon dioxide forming calcium carbonate. Hence carbon dioxide and monoxide is eliminated leaving nitrogen, and the rare gases
There is an explanation video available below.
42.

In the laboratory preparation of oxygen, the gas cannot be collected by downward displacement of air because

A. the density of oxygen is greater than that of air

B. the density of air is nearly the same as that of oxygen

C. oxygen is a component of air

D. air is an impure substance

Detailed Solution

Oxygen is collected in downward displacement of water because:-
There is an explanation video available below.
43.

2KClO\(_3\)(s) → 2KCl(s) + 3O\(_2\)(g)
The importance of the catalyst in the reaction above is that

A. heating may not be required before the reaction takes place

B. the reaction is controllable even at a high temperature

C. the reaction produces large quantity of oxygen

D. the reaction takes place more rapidly at a lower temperature

Detailed Solution

A catalyst is a substance that enables a chemical reaction to proceed at a usually faster rate or under different conditions (as at a lower temperature) than otherwise possible.
There is an explanation video available below.
44.

Which of the following is used to power steam engines?

A. lubricating oil

B. coal

C. bitumen

D. diesel oil

Detailed Solution

When we burn coal on a fire, the bonds break apart and the energy is released in the form of heat. Coal contains about half as much energy per kilogram as cleaner fossil fuels such as gasoline, diesel, and kerosene—and that's one reason why steam engines have to burn so much of it.
Coal is the fuel used to power steam engines.
There is an explanation video available below.
45.

In the reaction between sodium hydroxide and sulphuric acid solutions, what volume of 0.5 molar sodium hydroxide would exactly neutralise 10cm3 of 1.25 molar sulphuric acid?

A. 5cm\(^3\)

B. 10cm\(^3\)

C. 20cm\(^3\)

D. 50cm\(^3\)

Detailed Solution

2NaOH + H\(_2\) SO\(_4\)↔Na\(_2\)SO\(_4\) + 2H\(_2\)O
V x 0.5M = 2(10 x 1.25)
0.5V = 2 x 12.5
0.5V = 25
V = 250.5 = 50cm\(^2\)
Correct computation as it follows the equation specified.
There is an explanation video available below.
46.

To what volume must 300cm\(^3\) of 0.60M sodium hydroxide solution be diluted to give a 0.40M solution?

A. 450cm\(^3\)

B. 300cm\(^3\)

C. 200cm\(^3\)

D. 150cm\(^3\)

Detailed Solution

From the dilution law
C\(_1\)V\(_1\) = C\(_2\)V\(_2\)
C\(_1\) = Initial Concentration of NaOH = 0.6M
V\(_1\) = Initial Volume of NaOH = 300cm3
C\(_2\) = Final Concentration of NaOH = 0.4M
V\(_2\) = Final Volume of NaOH = ?
V\(_2\) = \(\frac{C_1V_1}{C_2}\)
V\(_2\) = \(\frac{0.6 \times 300}{0.4}\)
V\(_2\) = 450 cm\(^3\)
Correct Computation as it follows the equation specified
There is an explanation video available below.
47.

Diamond is a bad conductor of electricity because its bonding electrons are used in

A. crystal lattice formation

B. covalent bond formation

C. metallic bond formation

D. coordinate bond formation

Detailed Solution

Diamond is a covalent macromolecule, and typical of a covalent substance is an insulator. All valence electrons are localized in well-defined covalent bonds and hence are not free to move through the structure
There is an explanation video available below.
48.

The reaction between an organic acid and an alcohol in the presence of an acid catalyst is known as;

A. saponification

B. dehydration

C. esterification

D. hydrolysis

Detailed Solution

Esterification is a chemical reaction that forms at least one ester (= a type of compound produced by reaction between acids and alcohols). Esters are produced when acids are heated with alcohols in a process called esterification. An ester can be made by an esterification reaction of a carboxylic acid and an alcohol.
There is an explanation video available below.
49.

The constituent common to duralumin and alnico is

A. Co

B. Mn

C. Al

D. Mg

Detailed Solution

Constituents of duralumin are: Al, Cu, Mg, Mn.
Constituents of Alnico are: Al, Ni and Co
In 1909, the alloy of duralumin was discovered by Alfred Wilon consisting of 94% Al, 4% Cu, 1% Mg and 1% Mn(Manganese)
Alnico is an acronym referring to a family of iron alloys which in addition to iron are composed primarily of Al, Ni and Co.
There is an explanation video available below.
50.

The solubility of the solids that dissolves in a given solvent with the liberation of heat will

A. increase with an increase in temperature

B. decrease with an increase in temperature

C. decrease with a decrease in temperature

D. not be affected by changes in temperature

Detailed Solution

increasing temperature in exothermic reaction favors the left/reactant side and decreasing temperature will favor the right/product side.
There is an explanation video available below.
41.

When air which contains the gases Oxygen, nitrogen, carbondioxide, water vapour and the rare gases, is passed through alkaline pyrogallol and then over quicklime, the only gases left are;

A. nitrogen and carbondioxide

B. the rare gases

C. nitrogen and oxygen

D. nitrogen and the rare gases

Detailed Solution

The quick-lime is a drying agent that can dry most gases except ammonia. Hence it removes the water vapour. Quick-lime which is calcium oxide reacts with the carbon dioxide forming calcium carbonate. Hence carbon dioxide and monoxide is eliminated leaving nitrogen, and the rare gases
There is an explanation video available below.
42.

In the laboratory preparation of oxygen, the gas cannot be collected by downward displacement of air because

A. the density of oxygen is greater than that of air

B. the density of air is nearly the same as that of oxygen

C. oxygen is a component of air

D. air is an impure substance

Detailed Solution

Oxygen is collected in downward displacement of water because:-
There is an explanation video available below.
43.

2KClO\(_3\)(s) → 2KCl(s) + 3O\(_2\)(g)
The importance of the catalyst in the reaction above is that

A. heating may not be required before the reaction takes place

B. the reaction is controllable even at a high temperature

C. the reaction produces large quantity of oxygen

D. the reaction takes place more rapidly at a lower temperature

Detailed Solution

A catalyst is a substance that enables a chemical reaction to proceed at a usually faster rate or under different conditions (as at a lower temperature) than otherwise possible.
There is an explanation video available below.
44.

Which of the following is used to power steam engines?

A. lubricating oil

B. coal

C. bitumen

D. diesel oil

Detailed Solution

When we burn coal on a fire, the bonds break apart and the energy is released in the form of heat. Coal contains about half as much energy per kilogram as cleaner fossil fuels such as gasoline, diesel, and kerosene—and that's one reason why steam engines have to burn so much of it.
Coal is the fuel used to power steam engines.
There is an explanation video available below.
45.

In the reaction between sodium hydroxide and sulphuric acid solutions, what volume of 0.5 molar sodium hydroxide would exactly neutralise 10cm3 of 1.25 molar sulphuric acid?

A. 5cm\(^3\)

B. 10cm\(^3\)

C. 20cm\(^3\)

D. 50cm\(^3\)

Detailed Solution

2NaOH + H\(_2\) SO\(_4\)↔Na\(_2\)SO\(_4\) + 2H\(_2\)O
V x 0.5M = 2(10 x 1.25)
0.5V = 2 x 12.5
0.5V = 25
V = 250.5 = 50cm\(^2\)
Correct computation as it follows the equation specified.
There is an explanation video available below.
46.

To what volume must 300cm\(^3\) of 0.60M sodium hydroxide solution be diluted to give a 0.40M solution?

A. 450cm\(^3\)

B. 300cm\(^3\)

C. 200cm\(^3\)

D. 150cm\(^3\)

Detailed Solution

From the dilution law
C\(_1\)V\(_1\) = C\(_2\)V\(_2\)
C\(_1\) = Initial Concentration of NaOH = 0.6M
V\(_1\) = Initial Volume of NaOH = 300cm3
C\(_2\) = Final Concentration of NaOH = 0.4M
V\(_2\) = Final Volume of NaOH = ?
V\(_2\) = \(\frac{C_1V_1}{C_2}\)
V\(_2\) = \(\frac{0.6 \times 300}{0.4}\)
V\(_2\) = 450 cm\(^3\)
Correct Computation as it follows the equation specified
There is an explanation video available below.
47.

Diamond is a bad conductor of electricity because its bonding electrons are used in

A. crystal lattice formation

B. covalent bond formation

C. metallic bond formation

D. coordinate bond formation

Detailed Solution

Diamond is a covalent macromolecule, and typical of a covalent substance is an insulator. All valence electrons are localized in well-defined covalent bonds and hence are not free to move through the structure
There is an explanation video available below.
48.

The reaction between an organic acid and an alcohol in the presence of an acid catalyst is known as;

A. saponification

B. dehydration

C. esterification

D. hydrolysis

Detailed Solution

Esterification is a chemical reaction that forms at least one ester (= a type of compound produced by reaction between acids and alcohols). Esters are produced when acids are heated with alcohols in a process called esterification. An ester can be made by an esterification reaction of a carboxylic acid and an alcohol.
There is an explanation video available below.
49.

The constituent common to duralumin and alnico is

A. Co

B. Mn

C. Al

D. Mg

Detailed Solution

Constituents of duralumin are: Al, Cu, Mg, Mn.
Constituents of Alnico are: Al, Ni and Co
In 1909, the alloy of duralumin was discovered by Alfred Wilon consisting of 94% Al, 4% Cu, 1% Mg and 1% Mn(Manganese)
Alnico is an acronym referring to a family of iron alloys which in addition to iron are composed primarily of Al, Ni and Co.
There is an explanation video available below.
50.

The solubility of the solids that dissolves in a given solvent with the liberation of heat will

A. increase with an increase in temperature

B. decrease with an increase in temperature

C. decrease with a decrease in temperature

D. not be affected by changes in temperature

Detailed Solution

increasing temperature in exothermic reaction favors the left/reactant side and decreasing temperature will favor the right/product side.
There is an explanation video available below.