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.

561.

Which of the following arrangements indicates the correct decreasing order of ionization energy of period 3 elements?

A.

Na, Al, P, Cl

B.

Cl, P, Al, Na

C.

Na, P, Cl, Al

D.

Al, Na, P, Cl

Correct answer is B

As you move across a period, first ionization energy increases.

562.

The oxidation number of nitrogen in \(Pb(NO_{3})_{2}\) is

A.

+2

B.

+3

C.

+4

D.

+5

Correct answer is D

\(Pb(NO_{3})_{2}\) = \(+2 +2N + (-2\times 6) = 0\)

= \(2N = 10\)

⇒ \(N = +5\)

563.

The reason for the decrease in the atomic size of elements across a period is that

A.

nuclear charge increases while the outermost electrons are drawn closer to the nucleus

B.

nuclear charge decreases while the outermost electrons are drawn closer to the nucleus

C.

valence electrons increase across the period while the valence shell remains constant

D.

nuclear charge decreases while the distance of the valence shell from the nucleus is increasing

Correct answer is A

This is caused by the increase in the number of protons and electrons across a period.

564.

The property of elements which increases down a group of the periodic table is

A.

electronegativity

B.

electron affinity

C.

onic radius

D.

ionization energy

Correct answer is C

The ionic radius decreases across a period but increases along a group.

565.

Atomic orbital is

A.

the circular path through which electrons revolve round the nucleus

B.

a region around the nucleus where electrons are most likely to be found

C.

the path around the nucleus through which electrons move

D.

the path around the nucleus through which protons move

Correct answer is B

The orbital is a path or region around the nucleus. The electrons move in the orbitals and not through it.