NECO Past Questions and Answers - Page 85

421.

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      CH\(_3\)

422.

Which of the following non-metals reacts most readily with metals?

A.

Carbon

B.

Chlorine

C.

Nitrogen

D.

Phosphorus

E.

Sulphur

Correct answer is B

No explanation has been provided for this answer.

423.

Compound with the general formula CnH\(_{2n+2}\) belong to the_______ group

A.

alkanal

B.

alkane

C.

alkanoate

D.

alkene

E.

alkyne

Correct answer is B

Alkanes have the general formula of CnH2n+2 where n is the number of carbon atoms.

Alkenes have the general formula CnH2n.

The general formula for Alkynes is CnH2n-2.

424.

The process involved in the decomposition of sugar by an enzyme is called

A.

dehydration

B.

esterification

C.

fermentation

D.

polymerization

E.

saponification

Correct answer is C

No explanation has been provided for this answer.

425.

Which of the following equations is NOT balanced?

A.

CH4(g) + 202(9) → CO2(g) + 2H2O(g)

B.

CU(S) + HNO3(aq) → Cu(NO3)2(aq) + 4H2O(I) + NO(g)

C.

2KCIO3(s) → 2KCI(s)+ 3O2(g)

D.

NaH(s) + H2O(1) → NaOH(aq) +H2(g)

E.

Na2SO4(aq) + BaCl2(aq) → BaSO4(s) + 2NaCl(aq)

Correct answer is B

No explanation has been provided for this answer.