WAEC Physics Past Questions & Answers - Page 75

371.

The mass of an empty density bottle is 30g. When filled with a liquid, the mass of the bottle and the liquid is 40g. On heating the filled bottle through 40ºc, the mass reduces to 38g. Calculate the apparent cubic expansivity of the liquid

A.

6.25 x 10K-1

B.

6.25 x 10-3K-1

C.

2.50 x 10-3K-1

D.

2.50 x 10-4K-1

Correct answer is B

Apparent cubic expansivity = \(\frac{\text{mass of hot liquid expelled}}{\text{mass of hot liquid left x temp. rise}}\)

= \(\frac{2}{8 \times 40} = 0.00625\)

373.

A body of mass M kg rests on a plane inclined at an angle \(\theta\) to the horizontal. The component of the weight of the body parallel to the plane is

A.

Mg sin \(\theta\)

B.

Mg cos \(\theta\)

C.

Mg tan \(\theta\)

D.

Mg sec \(\theta\)

Correct answer is A

No explanation has been provided for this answer.

374.

Which of the following types of thermometers can be used to measure a range of temperature from -50°C to 50°? i. Clinical ii. Mercury iii. Alcohol-in-glass

A.

i only

B.

ii only

C.

iii only

D.

i and ii only

Correct answer is C

No explanation has been provided for this answer.

375.

The change of state from solid to liquid occurs

A.

at constant temperature

B.

when temperature is lower than the boiling point

C.

when temperature is just near freezing point

D.

when temperature is equal to the boiling point

Correct answer is A

No explanation has been provided for this answer.