Year : 
2020
Title : 
Chemistry
Exam : 
JAMB Exam

Paper 1 | Objectives

11 - 20 of 40 Questions

# Question Ans
11.

When water drops are added to calcium carbide in a container and the gas produced is passed through a jet and lighted, the resultant flame is called an?

A. Oxyethene

B. Oxyhydrocarbon flame

C. Oxyacetylene flame

D. Oxymethane flame

Detailed Solution

The reaction of calcium carbide with water, producing acetylene and calcium hydroxide, was discovered by Friedrich Wöhler in 1862. This reaction was the basis of the industrial manufacture of acetylene, and is the major industrial use of calcium carbide.
There is an explanation video available below.
12.

Which of the following substances is a mixture?

A. Granulated sugar

B. Seawater

C. Sodium chloride

D. Iron filling

Detailed Solution

A Mixture contains two or more constituents which can be easily separated by physical methods. Examples include Air, Soil, Palm oil, Sea water, Blood, Crude oil, etc
There is an explanation video available below.
13.

If the quantity of oxygen occupying 2.76L container at a pressure of 0.825 atm and 300k is reduced by one-half, what is the pressure exerted by the remaining gas?

A. 1.650atm

B. 0.825atm

C. 0.413atm

D. 0.275atm

Detailed Solution

Using the combined gas law formula,
Given that P\(_1\) = 0.825, V\(_1\) = 2.76 L, V\(_2\) = 1.38 L, P\(_2\) = ?
And T1 = T2; we would have P\(_2\) = [ P\(_1\) X V\(_1\) ] ÷ V\(_2\)
: [0.825 X 2.76] ÷ 1.38
= 1.650atm

There is an explanation video available below.
14.

Four elements P, Q, R and S have atomic numbers of 4, 10, 12 and 14 respectively. Which of these elements is noble gas?

A. P

B. Q

C. R

D. S

Detailed Solution

They are the most stable due to having the maximum number of valence electrons their outer shell can hold. Therefore, they rarely react with other elements since they are already stable.
There is an explanation video available below.
15.

The products of the thermal decomposition of ammonium trioxonitrate(v) are?

A. Nitrogen (I) Oxide and Water

B. Ammonia and Oxide

C. Nitrogen and Water

D. Nitrogen (IV) Oxide and Water

Detailed Solution

NH\(_4\)NO\(_3\) Ammonium Trioxonitrate(V) , unlike all other metallic trioxonitrates(v), decomposes on heating to give nitrogen(i)oxide N\(_2\)O and water.
There is an explanation video available below.
16.

How many valence electrons are contained in the element \(^{31}_{15}P\)?

A. 3

B. 4

C. 15

D. 31

Detailed Solution

The element is Phosphorus in group 5 with valencies of 3 and 5.
There is an explanation video available below.
17.

The number of molecules of Carbon(iv)Oxide produced when 10.0g of CaCO\(_3\) is treated with 0.2dm\(^3\) of 1 Mole of HCL in the equationCaCO\(_3\) + 2HCL ⇒ CaCl\(_2\) + H\(_2\) O + CO\(_2\) , is ?

A. 1.00 X 10\(^{23}\)

B. 6.02 X 10\(^{23}\)

C. 6.02 X 10\(^{22}\)

D. 6.02 X 10\(^{24}\)

Detailed Solution

There is an explanation video available below.
18.

The volume occupied by 1.58g of a gas at S.T.P is 500cm\(^3\). What is the relative molecular mass of the gas? [ G.M.V at S.T.P = 22.4dm\(^{3}\) ]

A. 28

B. 32

C. 44

D. 71

Detailed Solution

500cm\(^3\) of the gas weighed 1.58
: 22400cm\(^3\) of the gas weight

[22400 X 1.58g] ÷ [ 500 ]
= 71
There is an explanation video available below.
19.

Which of the following gases will rekindle a brightly splint?

A. NO\(_2\)

B. NO

C. N\(_2\)O

D. CL\(_2\)

Detailed Solution

Nitrogen(I)Oxide rekindles a brightly glowing splinter but extinguishes a feebly glowing one which is not hot enough to decompose the gas to liberate oxygen
There is an explanation video available below.
20.

The shape of ammonia molecule is?

A. Trigonal planar

B. Octahedral

C. Square planar

D. Tetrahedral

Detailed Solution

The ammonia molecule has a trigonal pyramidal shape with the three hydrogen atoms and an unshared pair of electrons attached to the nitrogen atom.
There is an explanation video available below.
11.

When water drops are added to calcium carbide in a container and the gas produced is passed through a jet and lighted, the resultant flame is called an?

A. Oxyethene

B. Oxyhydrocarbon flame

C. Oxyacetylene flame

D. Oxymethane flame

Detailed Solution

The reaction of calcium carbide with water, producing acetylene and calcium hydroxide, was discovered by Friedrich Wöhler in 1862. This reaction was the basis of the industrial manufacture of acetylene, and is the major industrial use of calcium carbide.
There is an explanation video available below.
12.

Which of the following substances is a mixture?

A. Granulated sugar

B. Seawater

C. Sodium chloride

D. Iron filling

Detailed Solution

A Mixture contains two or more constituents which can be easily separated by physical methods. Examples include Air, Soil, Palm oil, Sea water, Blood, Crude oil, etc
There is an explanation video available below.
13.

If the quantity of oxygen occupying 2.76L container at a pressure of 0.825 atm and 300k is reduced by one-half, what is the pressure exerted by the remaining gas?

A. 1.650atm

B. 0.825atm

C. 0.413atm

D. 0.275atm

Detailed Solution

Using the combined gas law formula,
Given that P\(_1\) = 0.825, V\(_1\) = 2.76 L, V\(_2\) = 1.38 L, P\(_2\) = ?
And T1 = T2; we would have P\(_2\) = [ P\(_1\) X V\(_1\) ] ÷ V\(_2\)
: [0.825 X 2.76] ÷ 1.38
= 1.650atm

There is an explanation video available below.
14.

Four elements P, Q, R and S have atomic numbers of 4, 10, 12 and 14 respectively. Which of these elements is noble gas?

A. P

B. Q

C. R

D. S

Detailed Solution

They are the most stable due to having the maximum number of valence electrons their outer shell can hold. Therefore, they rarely react with other elements since they are already stable.
There is an explanation video available below.
15.

The products of the thermal decomposition of ammonium trioxonitrate(v) are?

A. Nitrogen (I) Oxide and Water

B. Ammonia and Oxide

C. Nitrogen and Water

D. Nitrogen (IV) Oxide and Water

Detailed Solution

NH\(_4\)NO\(_3\) Ammonium Trioxonitrate(V) , unlike all other metallic trioxonitrates(v), decomposes on heating to give nitrogen(i)oxide N\(_2\)O and water.
There is an explanation video available below.
16.

How many valence electrons are contained in the element \(^{31}_{15}P\)?

A. 3

B. 4

C. 15

D. 31

Detailed Solution

The element is Phosphorus in group 5 with valencies of 3 and 5.
There is an explanation video available below.
17.

The number of molecules of Carbon(iv)Oxide produced when 10.0g of CaCO\(_3\) is treated with 0.2dm\(^3\) of 1 Mole of HCL in the equationCaCO\(_3\) + 2HCL ⇒ CaCl\(_2\) + H\(_2\) O + CO\(_2\) , is ?

A. 1.00 X 10\(^{23}\)

B. 6.02 X 10\(^{23}\)

C. 6.02 X 10\(^{22}\)

D. 6.02 X 10\(^{24}\)

Detailed Solution

There is an explanation video available below.
18.

The volume occupied by 1.58g of a gas at S.T.P is 500cm\(^3\). What is the relative molecular mass of the gas? [ G.M.V at S.T.P = 22.4dm\(^{3}\) ]

A. 28

B. 32

C. 44

D. 71

Detailed Solution

500cm\(^3\) of the gas weighed 1.58
: 22400cm\(^3\) of the gas weight

[22400 X 1.58g] ÷ [ 500 ]
= 71
There is an explanation video available below.
19.

Which of the following gases will rekindle a brightly splint?

A. NO\(_2\)

B. NO

C. N\(_2\)O

D. CL\(_2\)

Detailed Solution

Nitrogen(I)Oxide rekindles a brightly glowing splinter but extinguishes a feebly glowing one which is not hot enough to decompose the gas to liberate oxygen
There is an explanation video available below.
20.

The shape of ammonia molecule is?

A. Trigonal planar

B. Octahedral

C. Square planar

D. Tetrahedral

Detailed Solution

The ammonia molecule has a trigonal pyramidal shape with the three hydrogen atoms and an unshared pair of electrons attached to the nitrogen atom.
There is an explanation video available below.