NECO Chemistry Past Questions & Answers - Page 26

126.

Chlorine is used in water purification because it

A.

bleaches impurities in the water

B.

decolorizes water

C.

destroys bacteria

D.

is extremely soluble in water

E.

is pleasant tasting

Correct answer is C

No explanation has been provided for this answer.

127.

Which statement is NOT true about the composition of starch?

A.

It contains only the atoms of carbon, hydrogen oxygen

B.

It is a polysaccharide

C.

Its empirical formula is C2H20.

D.

It is made from the monomerC6H12O6.

E.

The hydrogen and oxygen atoms are in the ratio 2:1.

Correct answer is C

No explanation has been provided for this answer.

128.

Which compound is a component of baking powder?

A.

Na2CO3

B.

Na2SO4

C.

KH2CO3

D.

NaHCO3

E.

NaHSO4

Correct answer is D

No explanation has been provided for this answer.

129.

if an element X with atomic number 13 combines with an element Y whose atomic number is 8 the most likely formula of the compound formed between X and Y is?

A.

XY

B.

X2Y

C.

XY2

D.

X3Y2

E.

X2Y3

Correct answer is E

Element X is aluminum of valency 3+

Element Y is oxygen of valency 2-

Their combination is \(Al_{2}O_{3}\)