Question 4836:

A piece of a radioactive material contains 100 atoms. If its half-life is 20 seconds, the time taking for 124 atoms to remain is _____________

A. 20 seconds
B. 40 seconds
C. 60 seconds
D. 80 seconds

Question 4837:

The percentage of the original nuclei of a sample of a radioactive substance left after 5 half-live is _____________

A. 8%
B. 5%
C. 3%
D. 1%

Question 4838:

The particle that is responsible for nuclear fission in a nuclear reactor is _____________

A. Neutron
B. Proton
C. Hectron
D. Photon

Question 4839:

Which of the following statement is true of the properties of a moving coil galvanometer?

A. The coil has a small area
B. There are strong heir springs to give a large control couple.
C. There is strong permanent magnet to give high magnetic flux
D. It has a small number of turns of coil.

Question 4840:

A bead travelling on a straight wire Is brought to rest at 0.2m by friction. If the mass of the bead is 0.01kg and the coefficient of friction between the bead and the wire is 0.1, determine the work done by the friction _____________

A. 2x \(10^{-4}\)J
B. 2 x \(10^{-3}\)j
C. 2 x \(10^{1}\)J
D. 2. x \(10^{2}\)
[g = 10 ms‘)