21. The pitch of an acoustic device can be increased by
- A. decreasing the loudness
- B. increasing the intensity
- C. increasing the frequency
- D. decreasing the intensity
22. One of the features of the fission process is that
- A. it leads to chain reaction
- B. its products are not radioactive
- C. neutrons are not released
- D. the of the masses of the reactants equals the sum of the masses of the products
23. The linear expansivity of brass is 2 x 10\(^{-5}\) C\(^{-1}\). If the volume of a piece of brass is 15.00cm at 0°C, what is the volume at 100°C
- A. 16.03cm\(^3\)
- B. 15.09cm\(^3\)
- C. 16.00cm\(^3\)
- D. 15.03cm\(^3\)
24. A lead bullet of mass 0.05 kg is fired with a velocity of 200 m/s into a lead block of mass 0.95 kg. Given that the lead block can move freely, the final kinetic energy after impact is
- A. 100J
- A. 150J
- C. 50J
- D. 200J
25. In a series R-L-C circuit at resonance, the voltages across the resistor and the inductor are 30V and 40V respectively. What is the voltage across the capacitor?
- A. 30V
- B. 70V
- C. 50V
- D. 40V
26. If the fraction of the atoms of a radioactive material left after 120years is , what is the half-life of the material?
- A. 20 years
- B. 10 years
- C. 2 years
- D. 24 years
27. 
In the diagram shown, which of the simple pendulum will resonate with P when set into oscillation?
- A. U
- B. T
- C. R and T
- D. Q and R
28. The time rate of loss of heat by a body is proportional to the
- A. temperature of its surroundings
- B. temperature of the body
- C. difference in temperature between the body and its surroundings
- D. ratio of the temperature of the body to that of its surroundings
29. A positively charged rod X is brought near an uncharged metal sphere Y and is then touched by a finger with X still in place. When the finger is removed, the result is that Y has
- A. no charge and a zero potential
- B. a positive charge and a zero potential
- C. a negative charge and a positive potential
- D. a negative charge and a negative potential
30. Electrical appliances in homes are normally earthed so that
- A. a person touching the appliances is safe from electric shock
- B. both the a.c. and d.c. sources can be used
- C. the appliances are maintained at a higher pd than the earth
- D. the appliances are maintained at a lower pd than the earth
