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NECO Chemistry Past Questions & Answers - Page 25

121.

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

View answer & explanation

Correct answer is E

Element X is aluminum of valency 3+

Element Y is oxygen of valency 2-

Their combination is $Al_{2}O_{3}$

122.

When an electric current is passed through a solution containing dilute tetraoxosulphate (Vi) acid, 190 cm³ of hydrogen gas is evolved. if the measurements were made at 26°C and 736 mmHg, what is the volume of hydrogen at s.t.p.?

A.

164 cm³

B.

168 cm³

C.

179.1.cm³

D.

201.5cm³

E.

546 cm³

View answer & explanation

Correct answer is B

No explanation has been provided for this answer.

123.

A measure of the degree of disorderliness in a chemical system is known as the

A.

activation energy

B.

enthalpy

C.

entropy

D.

equilibrium

E.

free energy.

View answer & explanation

Correct answer is C

No explanation has been provided for this answer.

124.

Fructose and glucose are

A.

allotropes of each other.

B.

both disaccharides

C.

dimere of each other.

D.

isomers of each other

E.

isotopes of each other

View answer & explanation

Correct answer is D

No explanation has been provided for this answer.

125.

Detergents are better than soaps for washing in hard water because

A.

hard water contains insoluble calcium salts.

B.

they contain bleaching powder.

C.

they contain palmitic acid.

D.

they do not form insoluble calcium and magnesium salts.

E.

they are organic compounds.

View answer & explanation

Correct answer is D

No explanation has been provided for this answer.

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