Year : 
2007
Title : 
Chemistry
Exam : 
JAMB Exam

Paper 1 | Objectives

21 - 30 of 47 Questions

# Question Ans
21.

Calculate the number of moles of HCl present in 20cm3 of a 0.75M solution of the acid

A. 0.015 mole

B. 0.038 mole

C. 3.800 moles

D. 1.500 moles

Detailed Solution

Number of moles = (conc. in mol/dm3*volume in cm3)/1000
(0.75 * 20)/100 = 0.015 mole
22.

The oxidation state of oxygen in tetraoxosulphate (VI) acid is

A. -4

B. -2

C. +4

D. -8

Detailed Solution

H2SO4
(O.N of hydrogen * 2 ) + O.N of sulphur + O.N of oxygen * 4 = 0
∴ 1 * 2 + 6 + 4x = 0
2 + 6 + 4x = 0
8 + 4x = 0
4x 0 - 8 = -8
4x = -8
x = -8/4 = -2
23.

MnO2(s) + xHCl(aq) → MnCl2(aq) + yH2O(l) + zCl2(g)
In theequation above, what are the values of x, y and z respectively

A. 2, 1, 2

B. 4, 1, 2

C. 4, 2, 1

D. 1, 2, 1

C
24.

Calculate the mass of chlorine gas which occupies a volume of 1.12dm3 at s.t.p
[Cl = 35.5, molar volume of gas at s.t.p = 22.4 dm3

A. 15.50 g

B. 7.10 g

C. 3.55 g

D. 1.80 g

Detailed Solution

2 * 35.5g of chlorine has a volume of 22.4 dm3 at s.t.p
∴ xg of chlorine will have a volume of 1.12 dm3
x = (1.12 * 35.5 * 2)/22.4 = 3.55g
25.

Which experiment led to the measurement of the charge on an electron?

A. Mass spectrometric experiment

B. Oil-drop experiment

C. Scattering α - particles

D. Discharge-tube experiment

Detailed Solution

In 1909, Robert Millikan and Harvey Fletcher conducted the oil drop experiment to determine the charge of an electron.
26.

What is the volume of oxygen required to burn complete 45 cm3 of methane at s.t.p?

A. 135.0 cm3

B. 180.0 cm3

C. 45.0 cm3

D. 90.0 cm3

Detailed Solution

CH4(g) + 2O2(g) → 2H2O(g) + CO2(g)
1 volume of methane will react with 90 cm3 of oxygen at s.t.p
27.

How many electrons are in the L shell of 3115P?

A. 5

B. 8

C. 18

D. 2

B
28.

If the electron configuration of a element is p1s2 2s2 2P5, how many unpaired electron are there?

A. 2

B. 8

C. 1

D. 4

C
29.

Which of the following decrease when a given mass of gas is compressed to half its initial volume?

A. Atomic radius of each

B. Average intermolecular distance

C. Frequency of collisions

D. Number of molecules presents

B
30.

The elements that belong to the third period of the periodic table are

A. Li, Be, Al and P

B. Na, P, O and Cl

C. B, C, N and O

D. Nz, Mg, S and Ar

D
21.

Calculate the number of moles of HCl present in 20cm3 of a 0.75M solution of the acid

A. 0.015 mole

B. 0.038 mole

C. 3.800 moles

D. 1.500 moles

Detailed Solution

Number of moles = (conc. in mol/dm3*volume in cm3)/1000
(0.75 * 20)/100 = 0.015 mole
22.

The oxidation state of oxygen in tetraoxosulphate (VI) acid is

A. -4

B. -2

C. +4

D. -8

Detailed Solution

H2SO4
(O.N of hydrogen * 2 ) + O.N of sulphur + O.N of oxygen * 4 = 0
∴ 1 * 2 + 6 + 4x = 0
2 + 6 + 4x = 0
8 + 4x = 0
4x 0 - 8 = -8
4x = -8
x = -8/4 = -2
23.

MnO2(s) + xHCl(aq) → MnCl2(aq) + yH2O(l) + zCl2(g)
In theequation above, what are the values of x, y and z respectively

A. 2, 1, 2

B. 4, 1, 2

C. 4, 2, 1

D. 1, 2, 1

C
24.

Calculate the mass of chlorine gas which occupies a volume of 1.12dm3 at s.t.p
[Cl = 35.5, molar volume of gas at s.t.p = 22.4 dm3

A. 15.50 g

B. 7.10 g

C. 3.55 g

D. 1.80 g

Detailed Solution

2 * 35.5g of chlorine has a volume of 22.4 dm3 at s.t.p
∴ xg of chlorine will have a volume of 1.12 dm3
x = (1.12 * 35.5 * 2)/22.4 = 3.55g
25.

Which experiment led to the measurement of the charge on an electron?

A. Mass spectrometric experiment

B. Oil-drop experiment

C. Scattering α - particles

D. Discharge-tube experiment

Detailed Solution

In 1909, Robert Millikan and Harvey Fletcher conducted the oil drop experiment to determine the charge of an electron.
26.

What is the volume of oxygen required to burn complete 45 cm3 of methane at s.t.p?

A. 135.0 cm3

B. 180.0 cm3

C. 45.0 cm3

D. 90.0 cm3

Detailed Solution

CH4(g) + 2O2(g) → 2H2O(g) + CO2(g)
1 volume of methane will react with 90 cm3 of oxygen at s.t.p
27.

How many electrons are in the L shell of 3115P?

A. 5

B. 8

C. 18

D. 2

B
28.

If the electron configuration of a element is p1s2 2s2 2P5, how many unpaired electron are there?

A. 2

B. 8

C. 1

D. 4

C
29.

Which of the following decrease when a given mass of gas is compressed to half its initial volume?

A. Atomic radius of each

B. Average intermolecular distance

C. Frequency of collisions

D. Number of molecules presents

B
30.

The elements that belong to the third period of the periodic table are

A. Li, Be, Al and P

B. Na, P, O and Cl

C. B, C, N and O

D. Nz, Mg, S and Ar

D