JAMB Chemistry Past Questions & Answers - Page 48

236.

What volume of 0.100M sodium trioxonitrate (V) solution contains 5g of solute.
[Na = 23, N = 14, O = 16]

A.

1.7 litres

B.

0.420 litres

C.

0.588 litres

D.

2.35 litres

Correct answer is C

No explanation has been provided for this answer.

237.

Elements in the periodic table are arranged in the order of their

A.

atomic numbers

B.

metallic character

C.

mass number

D.

relative atomic mass

Correct answer is A

No explanation has been provided for this answer.

238.

Which important nitrogen-containing compound is produced in Haber's process?

A.

NH\(_3\)

B.

NO\(_2\)

C.

NO

D.

HNO\(_3\)

Correct answer is A

No explanation has been provided for this answer.

239.

What mass of magnesium would be obtained by passing a current of 2 amperes for 2 hours 30 mins, through molten magnesium chloride?
[1 faraday = 96500C, Mg = 24]

A.

1.12g

B.

4.48g

C.

1.80g

D.

2.00g

Correct answer is D

Given  Data:

Time (T) = 2hrs 30mins 

where 2hrs =120mins

2hrs & 30mins = (120 + 30)mins = 150mins

150mins to Seconds = 150 x60 = 9,000s

Q = I x T

2 x 9,000 =18,000

where mg has valency of +2

So 2 x 96500 will discharge 24g of mg

and 18,000 will discharge xg of mg

2 x 96500 =24

18,000 =x

x = \(\frac{24 \times 18,000}{2 x 96500}\)

≈ 2.00g

240.

Which of the following gases contains the least number of atoms at s.t.p?

A.

1 mole of butane

B.

4 moles of chlorine

C.

3 moles of ozone

D.

7 moles of argon

Correct answer is D

4 moles of chlorine gas = 4Cl\(_2\) = 8 atoms of chlorine
3 moles of ozone = 3O\(_3\) = 9 atoms of oxygen
1 mole of butane = C\(_4\)H\(_{10}\)
7 mole of argon = 7Ar = 7 atoms of argon

Argon is a monoatomic noble gas with the least number of atoms.