Chemistry questions and answers

Chemistry Questions and Answers

Learn more about the properties, composition, and structure of substances (elements and compounds) with these Chemistry questions and answers. This Test can be used by students preparing for Chemistry in JAMB, WAEC, NECO or Post UTME.

471.

The two ions responsible for hardness in water are

A.

Ca\(^{2+}\) and / or Mg\(^{2+}\)

B.

K\(^+\) and / or Mg\(^{2+}\)

C.

Ca\(^{2+}\) and / or Li\(^+\)

D.

Ca\(^{2+}\) and / or Na\(^+\)

Correct answer is A

No explanation has been provided for this answer.

472.

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.

473.

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.

474.

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.

475.

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