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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.

751.

The number of oxygen molecules present in 16.0g of the gas is ______?
[Avogadro's number = 6.02 x 1023]

A.

6.02 x 1022

B.

6.02 x 1023

C.

3.01 x 1023

D.

1.51 x 1023

Correct answer is C

1 mole = Molar mass of gas = Avogadros number
32g of O2 = 6.02 x 1023
16g of O2 = x
x = 16×6.02×102332 = 3.01 x 1023

752.

Consider the following reaction equation:
C2H4(g) + 3O2(g) 2CO2(g) + 2H2O(g)

The volume of CO2(g) produced at s.t.p when 0.05 moles of C2H4(g) was burnt in O2(g) is
[Molar Volume of gas = 22.4dm3

A.

1.12dm3

B.

2.24dm3

C.

3.72dm3

D.

4.48dm3

Correct answer is B

volumemolar volume = 0.05

1 mole of ethane produces 2 moles of carbon(iv)oxide

∴ 0.05  mole of ethane will produce x moles of carbon(iv)oxide

= volume22.4 = 0.05 X 2 X 22.4 =  2.24dm3

753.

Which of the following trioxonitrate(V) salts would decompose on heating to form a metal?

A.

Cu(NO3)2

B.

AgNO3

C.

Pb(NO3)2

D.

KNO3

Correct answer is B

No explanation has been provided for this answer.

754.
755.

Which of the following oxides is ionic?

A.

P4O10

B.

MgO

C.

Al2O3

D.

SO2

Correct answer is B

No explanation has been provided for this answer.