JAMB Chemistry Past Questions & Answers - Page 31

151.

Soaps clean surfaces on the principle based on?

A.

viscosity

B.

floatation

C.

elasticity

D.

surface tension

Correct answer is D

Since the surface tension forces become smaller as the distance between water molecules increases, the intervening soap molecules decrease the surface tension.

152.

Which of the following is a form of calcium carbonate?

I. limestone
II. marble
III. chalk
Iv. egg-shells

A.

I only

B.

I, II and IV

C.

I and II only

D.

I, II, III, and IV

Correct answer is D

- Calcium trioxocarbonate (IV) occurs abundantly in earth's crust as limestone, chalk and marble

- Eggshell is made almost entirely of calcium carbonate (CaCO3) crystals.

153.

Neutrons were discovered by?

A.

James Chadwick

B.

Ernest Rutherford

C.

J.J Thompson

D.

John Dalton

Correct answer is A

 - Sir James Chadwick, was a British physicist who was awarded the 1935 Nobel Prize in Physics for his discovery of the neutron in 1932. 

- Ernest Rutherford postulated the nuclear structure of the atom, discovered alpha and beta rays, and proposed the laws of radioactive decay.

- Sir Joseph John Thomson was a British physicist and Nobel Laureate in Physics, credited with the discovery of the electron, the first subatomic particle to be discovered. 

- John Dalton was an English chemist, physicist and meteorologist. He is best known for introducing the atomic theory into chemistry

154.

The maximum electron in N shell is?

A.

2

B.

8

C.

18

D.

32

Correct answer is D

The N shell is the fourth orbit with 32 max number of electrons using 2n\(^2\)

155.

A sample of any of the following substances disappears after some time when exposed to air like camphor, naphthalene, or dry ice. This phenomenon is called?

A.

Sublimation

B.

Evaporation

C.

Diffusion

D.

Radiation

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.

Familiar substances that sublime readily include iodine, dry ice, menthol, and camphor.