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.

3,296.

Cathode rays causes an object placed behind a perforated anode to cast a shadow on the screen. This observation shows that the rays?

A.

are positively charged

B.

are negatively charged

C.

have mass

D.

travel in straight lines

Correct answer is D

Cathode rays travel in a straight line and can cast sharp shadows.

Cathode rays are negatively charged.

Electric field and magnetic field deflect cathode rays.

3,297.

If an atom is represented as \( _{11}^{23}X \), which of the following deduction is correct?

A.

it contains 12 protons

B.

it forms a covalent chloride

C.

its atomic number is 23

D.

it is an alkali metal

Correct answer is D

Sodium has atomic / proton number of 11 and belongs to Group 1[alkali metals] on the periodic table

3,298.

The basic assumption in the kinetic theory of gases that the collisions of the gaseous molecules are perfectly elastic implies that the?

A.

forces of attraction and repulsion are in equilibrium

B.

gaseous molecules can occupy any available space

C.

gaseous molecules will continue their motion indefinitely

D.

gases can be compressed

Correct answer is C

An elastic collision is an encounter between two bodies in which the total kinetic energy of the two bodies remains the same.

3,299.

A gas exerts pressure on its container because?

A.

the molecules of a gas collide with the walls of the container

B.

some of the molecules are moving faster than others

C.

of the collisions of the molecules with each other

D.

of the mass of the molecules of the gas

Correct answer is A

Gas pressure is the name given to the force exerted by gas particles colliding with the wall of their container.

3,300.

0.0075 mole of calcium trioxocarbonate (IV) is added to 0.015 mole of a solution of hydrochloric acid. The volume of gas evolved at s.t.p is?
[Molar volume of a gas at s.t.p = 22.4 dm3]

A.

224cm3

B.

168cm3

C.

112cm3

D.

100cm3

Correct answer is B

1mole of gas at STP = 22.4dm\(^3\)
0.0075 mole of CaCO3  = xdm\(^3\)

cross multiply;

where 22.4dm\(^3\) = 22400cm\(^3\)

x * 1 = 0.0075 * 22400 → 168cm\(^3\)

 the gas CO2 which evolved was gotten from CaCO3 so we use the number of moles of CaCO3 only