NECO Chemistry Past Questions & Answers - Page 24

116.

What change will occur to the equilibrium mixture
\( 2CrO^{2-}_4(aq) + 2H^+(aq) ⇔ Cr_2O^{2-}_7(aq) + H_2O(l) \) when excess sodium hydrogen solution is added?

A.

A yellow precipitate of Cr(OH)3 is formed

B.

An orange precipitate of Cr(OH)3 is formed

C.

The colour changes from orange to yellow

D.

The colour changes from yellow to orange

E.

There is no visible reaction.

Correct answer is C

No explanation has been provided for this answer.

117.

What is the IUPAC name of CH3CCI=C(CH3)2?

A.

2-chloro -3 methylbut -2yne

B.

2 -chloro -3 methylbut -2ene

C.

2 -chloro -3 methylbutene

D.

3- methyl -2-chlorobut -2-ene

E.

3- methyl -2. chlorobut -2 yne

Correct answer is B

No explanation has been provided for this answer.

118.

Which formula is used to indicate the degree of acidity of an acid?

A.

\( [H^+] = ^{\text{mass of acid relative}} molecular mass of acid \)

B.

F = number of H+ = ions x molar mass of the acid

C.

Kw = [H+][OH-]

D.

pH = - log10[H+]

E.

pKa = -log10Ka

Correct answer is D

No explanation has been provided for this answer.

119.

Which compound will give propane when it Is dehy drated by an excess of hot, concentrated tetraoxosvlphate(VI) acid?

A.

CH3CH2CHO

B.

CH3CH2CH2OH

C.

CH3CH2COQH

D.

CH3CH20CH

E.

CH3CH3OH

Correct answer is B

No explanation has been provided for this answer.

120.

A calcium atom and a calcium ion have the same

A.

chemical properties

B.

electric charge

C.

electronic structure

D.

number of electrons

E.

number of neutrons

Correct answer is E

No explanation has been provided for this answer.