Below are three statements about radioactivity or nuclear energy.
1 Neutrons emitted in nuclear fission can cause further fission.
2 The half-life of a radioactive substance is half the time taken for all its nuclei to decay.
3 The process that produces heat and light in the Sun is called nuclear fission.

Which of these statements is/are correct?

Answer:

11) A

1 – This statement is correct as neutrons emitted in nuclear fission can cause further fission

2 – The definition of half life is wrong. Half life is the time taken for the radioactivity of a specified isotope to fall to half its original value. 

3 – Nuclear FUSION creates heat and light in the Sun. 

Only statement 1 is correct. So A is correct.