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NECO Chemistry Past Questions & Answers - Page 8

36.

Which of the following statements is NOT correct of group VII elements? They

A.

are diatomic

B.

are good oxidizing agents

C.

are highly electronegative

D.

have high electron affinity

E.

have relatively low ionization potentials

Correct answer is E

No explanation has been provided for this answer.

37.

Which of the following is NOT a fraction of petroleum?

A.

Bitumen

B.

Coal

C.

Diesel

D.

Kerosene

E.

Petrol

Correct answer is B

No explanation has been provided for this answer.

38.

The scientist who discovered the zig-zag movement of gas molecules is

A.

Brownian

B.

Dalton

C.

Gay Lussac

D.

Graham

E.

Newton

Correct answer is A

No explanation has been provided for this answer.

39.

The following compounds decolorize acidified potassium tetraoxomanganate (VII) solution EXCEPT

A.

HOCH2 – CH2OH

B.

H2C –C =C– CH3

C.

H3C – HC = CH2

D.

H2C = CH2

E.

H3C – C =CH

Correct answer is A

No explanation has been provided for this answer.

40.

The percentage composition of a hydrocarbon is 79.2 carbon 20.8 hydrogen. Calculate its empirical formula [H = 1, C = 12]

A.

CH

B.

CH3

C.

CH4

D.

C2H2

E.

C2H6

Correct answer is B

Relative No of Moles for Carbon = 79.2% ÷ 12 = 6.6

Relative No of Moles for Hydrogen = 20.8% ÷ 1 = 20.8

Ratio of Moles = Carbon 6.6 ÷ 6.6 = 1                 Hydrogen = 20.8 ÷ 6.6 ~ 3

EMPIRICAL FORMULA IS      CH3