Question 4746:

Which of the following is used in a nuclear reactor to slow down fast moving electrons?

A. Carbon dioxide gas
B. Liquid sodium metal
C. Concrete shield
D. Graphite rods.

Question 4747:

Calculate the power-rating of a heating element which melted in \(20 g\) of ice at \(0^{\circ} C\). and raised the temperature of the resulting water to \(60^{\circ} C\) in 2 minutes Specific latent heat of fusion of ice \(=340 V / g\) Specific heat capacity of water \(=4.2 J / 9^{\circ} C\)

A. \(5.92 kw\)
B. \(98.6 w\)
C. \(107 w\)
D. \(42 w\)

Question 4748:

If a man cannot see objects very close to him the following can be used to correct the problem.

A. Convex lens
B. Convex mirro
C. Concave lens
D. Concave mirro

Question 4749:

when the bob of a simple pendulum is at it's highest displacement, one of the following happens ____________

A. Kinetic energy is maximum
B. Potential energy is maximum
C. Total energy is zero
D. Momentum is maximum

Question 4750:

When the atmospheric pressure is very low in a given location, boiling point of water ____________

A. Increases
B. Decreases
C. Remains
D. Cannot boil