NECO Chemistry Past Questions & Answers - Page 33

161.

The position of an element in the Periodic Table is determined by?

A.

its atomic radius.

B.

its density.

C.

its relative atomic mass.

D.

the number of protons in its atom.

E.

the number of neutrons in its atoms

Correct answer is D

In the modern periodic table, the elements are listed in order of increasing atomic number. 

The atomic number is the number of protons in the nucleus of an atom.

162.

Which element contains the greatest number of moles?

A.

8 g of Helium

B.

48 g of Carbon

C.

78 g of Potassium

D.

130g of Zinc

E.

216g of Sliver

Correct answer is B

No explanation has been provided for this answer.

163.

The use of sulphur to vulcanize rubber is mad to make it

A.

blacker

B.

cheaper

C.

more elastic

D.

tougher

E.

softer

Correct answer is D

No explanation has been provided for this answer.

164.

The atomic number of iron is 56. The number of unpaired electrons in the Fe3+ ion is

A.

1

B.

2

C.

3

D.

4

E.

5

Correct answer is E

-There are 4 unpaired electrons in Fe

-However; 5 unpaired electrons are present in Fe3+

165.

Animal charcoal differs from wood charcoal in that it

A.

has a dark colour

B.

has a high carbon content

C.

is a good absorbent

D.

is crystalline.

E.

is rich in phosphate content

Correct answer is E

Animal charcoal or bone black is the carbonaceous residue obtained by the dry distillation of bones. It contains only about 10% carbon, the remaining being calcium and magnesium phosphates (80%) and other inorganic material originally present in the bones.