Waec Physics 2019 Past Questions and Answers

Question 36:

• WAEC 2019

A small amount of air is introduced into the vacuum above the mercury in a mercury barometer tube. The mercury level goes down because the air molecules

A. Heat the mercury and make it expand
B. Increase the pressure above the mercury.
C. Cool the mercury and make it contract.
D. Decrease the pressure above the mercury

Question 37:

• WAEC 2019

Calculate the quantity of heat needed to change the temperature of 60g of ice at 0 °C to 80 °C. [specific latent heat of fusion of ice= 3.36 x 10\(^5\) Jkg\(^{-1}\) specific heat capacity of water 4.2 x 10\(^3\) J kg\(^{-1}\) K\(^{-1}\)]

A. 4.80 kJ
B. 20.16 kJ
C. 40.32 kJ
D. 22.17 kJ

Question 38:

• WAEC 2019

The wire of a platinum resistance thermometer has d resistance of 3.5\(\Omega\) at 0 °C and 10.52\(\Omega\) at 100°C. Calculate the temperature of the wire when its resistance is 7.5\(\Omega\).

A. 78 °C
B. 25 \(^o\)C
C. 30\(^o\)C
D. 57 \(^o\)C

Question 39:

• WAEC 2019

A transverse pulse of frequency 9 Hz traves 4.5m in 0.6 s. Calculate the wavelength of the pulse.

A. 3.33 m
B. 0.30 m
C. 0.83 m
D. 1.20 m

Question 40:

• WAEC 2019

In which of the following media is the speed of sound the least?

A. Air
B. Brass
C. Water
D. Wood