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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.

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1,176.

Which of the following statements about a chemical system in equilibrium is correct/ The

reaction is irreversible

reaction goes to completion

equilibrium is re-established when a stress is applied

equilibrium position is affected by catalyst

View answer & explanation

Correct answer is C

No explanation has been provided for this answer.

1,177.

The mass of 800cm3 of gas Q at s.t.p. is 1.0g. What is the molar mass of Q? [Avogadros constant = 22.4dm3 mol-1`]

18.0 gmol^-1

22,4gmol^-1

28.0gmol^-1

36.0 gmol^-1

View answer & explanation

Correct answer is C

Imole Q occupies 22400 cm3
x mole occupies 800 cm3
x = $\frac{800 x 1}{22400}$
= 0.036mol

Molar mass = Mass ÷ Mole

= 1 ÷ 0.036

Molar mass ≈ 28 g/mol

1,178.

If 0.20 mol dm^-3 NaOH_(aq) was evaporated to yield 5.0g of solid NaOH, calculate the volume of NaOH _(aq) used. (Na = 23.0,O = 16:0; H = 1.00)

600cm-³

625cm³

1000³

1600 cm ³

View answer & explanation

Correct answer is B

Mole = 5/40 = 0.125 mole
:. 0.2 mole NaOH dissolved in 1000 cm³
0.125 mole NaOH dissolved in xcm³
xcm³ = $\frac{0.215 x 1000}{0.2}$
= 625cm³

1,179.

The oxidation number of sulphur in Fe₂(SO₄)₃ is

+2.

+4.

+6.

View answer & explanation

Correct answer is D

Fe₂(SO₄)₃ = 0
(+3 x 2) 9 3x + (-2 x 4 x 3) = 0
+6 + 3x -24 = 0
+3x - 18 = 0
3 x = 18
x = 18/3 = +6

1,180.

A gaseous mixture contains 0,256 g of hydrogen and 2.00 g of oxygen. The mole ration of hydrogen to oxygen in the mixture is (H=1.00; O=16,0)

1:1

2:1

1:4

8:1

View answer & explanation

Correct answer is B

Mole = $\frac{Mass}{Molar Mas}$ : $\frac{Mass}{Molar Mass}$
$\frac{0.256}{2}$ : $\frac{2}{32} 0. 128 : 0.0625 \(\frac{0.128}{0.0625}$ : $\frac{0.0625}{0.0625}$
2 : 1