The ground is always cold at night because the

• A) atmosphere absorbs the sun's energy at night
• B) earth radiates heat to the atmosphere at night
• C) sun no longer shine at night
• D) atmosphere reflects the sun's energy at night

A machine is used to lift a load of 20 N through a height of 10 m. if the efficiency of the machine is 40%, how much work is done?

• A) 80 J
• B) 500 J
• C) 300 J
• D) 120 J

A cannon is fired from town X,after how long is the sound heard at a town Y 4.95 km away?

[velocity of sound in the air = 330 m/s]

• A) 30 s
• B) 10 s
• C) 10 s
• D) 15 s

Which of the following types of waves needs a medium for propagation?

• A) sound waves
• B) light waves
• C) radio waves
• D) x - rays

An image in a convex lens is upright and magnified 3 times. If the focal length of the lens is 15 cm, what is the object distance?

• A) 10 cm
• B) 25 cm
• C) 16 cm
• D) 14 cm

The phenomenon that shows that increase in pressure lowers the melting point can be observed in

• A) sublimation
• B) condensation
• C) coagulation
• D) regelation

In homes, electrical appliances and lamps are connected in parallel because

• A) Parallel connections do not heat up the wires
• B) series connections use high voltage
• C) less current will be used
• D) less voltage will be used

I. Density of the liquid.

II. Depth below the surface of the liquid.

III. Surface area of the liquid.

In which of the statement above will pressure be dependent?

• A) I and II only
• B) II and III only
• C) I, II and III only
• D) I and III only

I. change of state

II. Diffusion

III. Radiation

IV. Osmosis

Which of the processes above can be explained using the kinetic theory?

• A) I, II,III and IV
• B )I, II and III
• C) I, III and IV
• D) I, II and IV

An object weighs 22 kg in water and 30kg in air. what is the upthrust exerted by the liquid on the object.

[g = 10 ms²]

• A) 50 N
• B) 520 N
• C) 220 N
• D) 80 N