Chemistry questions and answers

Chemistry Questions and Answers

Learn more about the properties, composition, and structure of substances (elements and compounds) with these Chemistry questions and answers. This Test can be used by students preparing for Chemistry in JAMB, WAEC, NECO or Post UTME.

371.

consider the following reaction equation: 2NH\(_3 \) .+ 3Cl\(_2\) → N2 + 6HCl. 

NH\(_3\) is acting as?

A.

a reducing agent

B.

a dehydrating agent

C.

a drying agent

D.

an oxidizing agent

Correct answer is A

- As a reducing agent, Ammonia reacts with chlorine to create nitrogen gas and hydrogen chloride vapour in the first step.

372.

If a catalyst is added to a system, the temperature and the pressure remain constant, there would be no effect on the? 

A.

activation energy of the reaction

B.

rate of the reaction

C.

rate of the reverse reaction

D.

heat of reaction

Correct answer is D

No explanation has been provided for this answer.

373.

Which of the following reagents could be used to distinguish between propan-1-ol and propan-2-ol

A.

H+ / K2Cr2O7

B.

I\(_2\) / OH-

C.

CH\(_3\)COOH

D.

NaCl

Correct answer is A

when a primary alcohol like ethanol is warmed with excess of an oxidizing reagent, such as acidified Potassium permanganate( KMnO₄) or acidified Potassium dichromate(VI) ( K2Cr2O7 ), it is oxidized first to ethanal then to ethanoic acid, WHILE

Secondary alcohols like butan-2-ol will be oxidized to alkanones

propan-1-ol - primary alcohol,

propan-2-ol- secondary alcohol

- The Lucas test in alcohols is a test to differentiate between primary, secondary, and tertiary alcohols. It is based on the difference in reactivity of the three classes of alcohols with hydrogen halides 

374.

When excess chlorine is mixed with ethane at room temperature, the product formed is?

A.

1,2-dichloroethane

B.

1,2-dichloroethene

C.

1,1-dichloroethane

D.

1,1-dichloroethene

Correct answer is A

- The chemical compound 1,2-dichloroethane, commonly known as ethylene dichloride (EDC), is a chlorinated hydrocarbon

375.

An organic compound contains 72% carbon, 12% hydrogen and 16% oxygen by mass. What is the empirical formula of the compound?

[ H = 1.0. C = 12.0, O = 16.0 ]

A.

C\(_3\)H\(_8\)O

B.

C\(_6\)H\(_12\)O

C.

C\(_6\)H\(_12\)O\(_2\)

D.

C\(_12\)H\(_12\)O\(_11\)

Correct answer is B

C = 72 / 12       H = 12 / 1       O = 16 / 16

C = 6               H = 12             O = 1

: EMPIRICAL FORMULA

C\(_6\)H\(_12\)O