Fig. 11.1 represents a nuclear fusion reaction. At very high temperatures, nuclei of the two isotopes ³H and ²H fuse together. Energy is produced and two new particles are formed, particle A and particle B.

1. (a)Explain what is meant by isotopes of hydrogen.[2]
2. (b)(i)Using Fig. 11.1, state (i) the number of neutrons in a nucleus of the isotope ³H,[1]
3. (b)(ii)(ii) the name of particle A,[1]
4. (b)(iii)(iii) the proton number of particle B,[1]
5. (b)(iv)(iv) the nucleon number (mass number) of particle B.[1]
6. (c)A very high temperature is needed to force nuclei together. Explain why.[2]
7. (d)A star forms from a large cloud of gas and dust in space. Describe what happens as the star forms.[3]
8. (e)(i)State what is meant by half-life.[2]
9. (e)(ii)A sample contains 16000 atoms of ³H. Calculate the number of atoms of ³H present in the sample after 48 years.[2]

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