WAEC Chemistry Past Questions & Answers - Page 58

286.

The species with no electron in the 3d-orbital is

A.

\(Zn^{2+}\)

B.

\(Sc^{3+}\)

C.

Cu

D.

\(Mn\)

Correct answer is B

Scandium has electronic configuration \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{1}4s^{2}\) hence, \(Sc^{3+}\) has configuration \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}\). Hence, no electron in the 3d-orbital.

287.

Pauli exclusion principle is related to

A.

quantity of electrons in the valence shell

B.

filling the orbitals with lower energy first

C.

the filling of degenerated orbitals

D.

quantum numbers of electrons

Correct answer is D

Pauli Exclusion Principle states that, in an atom or molecule, no two electrons can have the same four electronic quantum numbers.

288.

The following glasswares are used to measure the volume of liquids EXCEPT

A.

graduated beaker

B.

pipette

C.

test tube

D.

burette

Correct answer is C

Test tubes are convenient containers for heating small amounts of liquids or solids with a Bunsen burner or alcohol burner.

289.

Which of the following species determines the chemical properties of an atom?

A.

Electron

B.

Neutron

C.

Nucleus

D.

Proton

Correct answer is A

An element's chemical properties depend on its valence electrons.The chemical properties of elements depend on an element's electron configuration.

290.

Particles in a solid exibit

A.

vibrational motion

B.

vibrational and translational motion

C.

vibrational and random motion

D.

random and translational motion

Correct answer is A

Solids vibrate but generally do not move from place to place.