WAEC Chemistry Past Questions & Answers - Page 174

866.

When sodium atom form the ion Na+,

A.

it gains one proton

B.

it achieves a noble gas configuration

C.

its atomic number increases

D.

it gains one electron

Correct answer is B

When the sodium atom forms an ion, Na+ it loses one electron, i.e. it achieves a noble gas electronic configuration. It will lose one of its 11 electrons to have 10 electrons like neon.
\(Na - e^- → Na^+\)
Na → \(Na^+ + e^-\)

867.

Which of the following equations represents a substitution reaction?

A.

C 2H10(g) + CI 2(g) → C4H9 CI(g) + HCI(g)

B.

C 2H4(g) + HCI (g) → C 2H5 CI(l)

C.

C2H2(g) + 2H 2(g) → C 2H6(g)

D.

C 3H4(g) + 402(g) → 3CO2(g) + 2H 2O(g)

Correct answer is A

No explanation has been provided for this answer.

868.

The ammonium compound used in the manufacture of dry cells is

A.

NH4NO3

B.

(NH4)SO4

C.

NHCI4

D.

(NH4)2CO3

Correct answer is C

No explanation has been provided for this answer.

869.

Which of the following substance is an ore of iron?

A.

Bauxite

B.

Cassiterite

C.

Haematite

D.

Steel

Correct answer is C

No explanation has been provided for this answer.

870.

Waste plastics accumulate in the soil and pollute the environment because plastic materials are

A.

insoluble in water

B.

non -biodegradable

C.

easily affected by heat

D.

inflammab,le

Correct answer is B

No explanation has been provided for this answer.