JAMB Chemistry Past Questions & Answers - Page 431

2,152.

1s2, 2s2, 2p6, 3s2, 3p6, 3d7, 4s2
An element with the electronic configuration above is a

A.

non-metal

B.

metal

C.

transition element

D.

group two element

Correct answer is C

No explanation has been provided for this answer.

2,153.

The method that can be used to convert hard water to soft water is

A.

chlorination

B.

passage over activated charcoal

C.

the use of an ion-exchange resin

D.

aeration

Correct answer is C

No explanation has been provided for this answer.

2,154.

Nitrogen obtained from the liquefaction of air has a higher density than that obtained from nitrogen containing compounds because the former contains

A.

water vapour

B.

oxygen

C.

carbon (IV) oxide

D.

rare gases

Correct answer is D

The correct answer is rare gases because when nitrogen is obtained from air, \(CO_2\) and \(O_2\) are removed by passing air through caustic soda and heated copper turnings respectively.
However, the nitrogen obtained this way contains about 1% by volume of rare gases as impurities, these rare gases make it denser than nitrogen obtained from nitrogen compounds like ammonia, etc

2,155.

In order to remove one electron from a 3S orbital of gaseous sodium atom, about 496KJMol-1 of energy is required. This energy is referred to as

A.

electron affinity

B.

ionization energy

C.

activation evergy

D.

electronegativity

Correct answer is B

No explanation has been provided for this answer.