Calculate the heat energy required to vaporize 50g of water initially at 80ºC if the specific heat capacity of water is 4.23jg^−1k^−1 (specific latent heat of vaporization of water is 2260jg^−1

• A. 530000J
• B. 23200J
• C. 17200J
• D. 130000J

The product PV where P is pressure and V is volume has the same unit as

• A. power
• B. work
• C. acceleration
• D. impulse

A force of 40 N is applied at the end of a wire 4m long and produces an extension of 0.24mm. If the diameter of the wire is 2.00mm, calculate the;

(i) stress on the wire; (ii) strain in the wire.

A current of 0.5 A flowing 3h Deposits 2g of metal during electrolysis. The quantity of the same metal that would be deposited by the currents of 1.5A flowing in 1h is

• A. 2g
• B. 6g
• C. 10g
• D. 18g

(a) Define binding energy in an atom.

(b) List three evidence to support the claim that X-rays are electromagnetic waves.

(c) List three peaceful uses of nuclear energy.

(d) Light of wavelength 4.5 x 10\(^{-7}\) in is incident on a metal resulting in the emission of photo electrons. If the work function of the metal is 3.0 x 10\(^{-9}\) J, calculate the:

(i) frequency of the incident light;

(ii) energy of the incident light;

(iii) energy of the photoelectrons. [Speed of light = 3.0 x 10\(^8\) ms\(^{-1}\), h = 6.6 x 10\(^{-34}\) Js]

An object of mass 400g and density 600kgm^-3 is suspended with a sting so that half of it is immersed in paraffin of density 900kgm^-3. The tension in the string is

• A. 1.0N
• B. 3.0N
• C. 4.0N
• D. 5.0N

Which of the following electromagnetic waves is least energetic?

• A. Infra-red rays
• B. X-rays
• C. Ultra-violet rays
• D. Gamma rays

Two horizontal forces, 10N and 8N and another force F1 inclined at 30 to the vertical acting as shown in the diagram below, keep the body P in equilibrium, The weight of the body is

• A. 2?3/3N
• B. ?2N
• C. 4?3/3
• D. 2V3N

The velocity y of a particle in a time t is given by the equation y = 10 + 2t²

Find the instantaneous acceleration after 5 seconds

• A. 60 ms^-2
• B. 20 ms^-2
• C. 15 ms^-2
• D. 10 ms^-2

Which of the following condition is necessary for the occurrence of total internal reflection of light?

• A. light must travel from an optical less dense to a denser medium
• B. the angle of incidence must be equal to the critical angle
• C. the angle of incidence must be greater than the critical angle
• D. the angle of refraction must be 90°