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.

586.

The number of Hydrogen ions in 1.0\(dm^{3}\) of 0.02\(moldm^{-3}\) tetraoxosulphate(VI) acid is   \([N_{A} = 6.02 \times 10^{23}]\)

A.

\(1.2 \times 10^{22}\)

B.

\(1.2 \times 10^{23}\)

C.

\(2.4 \times 10^{22}\)

D.

\(2.4 \times 10^{23}\)

Correct answer is A

\(1mole = 6.02 \times 10^{23} ions\)

\(0.02moldm^{-3} = 0.02 \times 6.02 \times 10^{23}\)

=\(0.1204 \times 10^{23} = 1.204 \times 10^{22}\)

\(\approxeq 1.2 \times 10^{22}\)

587.

Stainless steel is an alloy comprising of

A.

Fe and C

B.

Fe and Ni

C.

Fe, C and Ni

D.

Fe, C and Al

Correct answer is C

Stainless steel comprises iron (Fe), chromium (Cr), manganese (Mn), silicon (Si), carbon (C) and, in many cases, significant amounts of nickel (Ni) and molybdenum (Mo).

588.

The valence electrons of \(_{12}Mg\) are in the

A.

3s orbital

B.

2p\(_{x}\)

C.

2s orbital

D.

1s orbital

Correct answer is A

\(_{12}Mg = 2, 8, 2\)

\(= 1s^{2} 2s^{2} 2p^{6} 3s^{2}\)

589.

The preferential discharge of ions during electrolysis is influenced by the 

A.

mechanism of electrolysis

B.

electrolytic reactions

C.

nature of the electrode

D.

type of electrolytic cell

Correct answer is C

The preferential discharge of ions is influenced by:

- The position of the ions in the electrochemical series

- The concentration of the ions in the electrolyte

- The nature of the electrode

590.

When substance X was added to a solution of bromine water, the solution became colourless. X is likely to be

A.

propane

B.

propanoic acid

C.

propyne

D.

propanol

Correct answer is C

Thus bromine water will be decolorized by alkynes due to the presence of two pi bonds available for reaction!