Two plane mirrors are inclined at an angle 20° to each other. Determine the number of images formed when an object is placed between them.

• A. 17
• B. 18
• C. 19
• D. 20

If an object just begins to slide on a surface inclined at 30o to the horizontal,the coefficient of friction is

• A. √3
• B. √3/2
• C. 1/√2
• D. 1/√3

The working of the beam balance is based on the principle of

• A. moments
• B. conservation of energy
• C. equivalence
• D. floatation

Which of the following observations is not an effect of surface tension?

• A. droplets of water dripping slowly from a tap
• B. mercury spilled on a clean glass plate forms spherical droplets
• C. an indect walking across the surface of a pond
• D. water flowing out more easily then engine oil from a container

The external parts of an object can be measure accurately through the use of which scientific instrument?

• A. Micrometer screw gauge
• B. Vernier Caliper
• C. Meter rule
• D. None of the instrument

The angle of deviation of light of various colours passing through a triangular prism increases in the order

• A. red → green → blue
• B. green → violet → blue
• C. blue → red → green
• D. blue → green → red

(a) Define nucleon number

(b) A radioactive isotope of Americium (Am —241) decays into a nucleus of Neptunium (Np — 237) and an alpha (\(\alpha\)) particle as shown in the nuclear equation below. \(^{241}_{95}Am\) \(\to\) \(^{237}_{c} + ^b_a \alpha\)

(i) State the number of neutrons in the nucleus of Americium — 241.

(ii) Determine the values of a,b and c.

(c)(i) Why are y-rays not deflected by electromagnetic field?

(ii) State two properties of gamma rays that make them suitable for sterilizing medical equipment.

(d) A sample of radioactive substance was found to be left with h of its initial count rate after 110 years. Calculate its decay constant.

The ability of a material to store an electric charge when its plates are at different potentials is referred to as its

• A. conductance
• B. inductance
• C. capacitance
• D. resistance

A body starts from rest and moves with uniform acceleration of 6ms^-2. What distance does it cover in the third seconds

• A. 15m
• B. 18m
• C. 27m
• D. 30m

The electrochemical equivalent of platinum is 5.0 x 10^-7kgC^-1 to plate-out 1.0kg of platinum, a current of 100A must be passed through an appropriate vessel for

• A. 5.6 hours
• B. 56 hours
• C. 1.4 x 10^{4 hours}
• D. 2.0 x 10^{4 hours}