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.

406.

An electron can be added to a halogen atom to form a halide ion with?

A.

8 valence electrons

B.

7 valence electrons

C.

2 valence electrons

D.

3 valence electrons

Correct answer is A

halide ion is a halogen atom bearing a negative charge (which is an anion with a charge of -1). The halide anions are fluoride (F−), chloride (Cl−), bromide (Br−), iodide (I−) and astatide (At−).

407.

When a solid substance disappears completely as a gas on heating, the substance is said to have undergone?

A.

Sublimation

B.

Crystallization

C.

Distillation

D.

Evaporation

Correct answer is A

Sublimation is the transition of a substance directly from the solid to the gas state, without passing through the liquid state.

408.

When cathode rays are deflected onto the electrode of an electrometer, the instrument becomes?

A.

Bipolar

B.

Negatively charged

C.

Positively charged

D.

Neutral

Correct answer is B

When these cathode rays are deflected onto an electrode of an electrometer, the instrument measured a negative charge. The rays tested also were deflected by application of an electric field.

409.

The general formula for the Alkanals is?

A.

R\(_2\)CO

B.

RCHO

C.

ROH

D.

RCOOR

Correct answer is B

Alkanals or Aldehydes have the general formula RCHO while Alkanones or Ketones have the general formula RCOR'.

Where R and R' may be alkyl or aryl groups.

410.

Proteins in acid solution undergo?

A.

Substitution

B.

Fermentation

C.

Hydrolysis

D.

Polymerisation

Correct answer is C

Acid hydrolysis refers to a hydrolysis reaction occurring under acidic conditions. Acid hydrolysis of a protein breaks the polymer down into its constituent amino acids.