

Explanation
(a) Conclusion from Rutherford's experiment;
- The nucleus is massive
- Most of the atom is empty space
- The nucleus is positively charged
- Electrons revolve round the nucleus
- It explains the periodicity of elements in the periodic table

b )(i) E\(_2\) = E\(_2\) - E\(_o\)
= - 2.0 - (-12.0)
= 10.0 e V 
= 10 x 1.6 x 1O\(^{-19}\)J
= 1.6 x 10\(^{-18}\)J
E = hf

Or
f = E/h
= 1.6 x 10\(^{18}\)
= 6.6 x10\(^{-34}\)
= 2.424 x 10\(^{15}\) Hz

(ii) c = fÎ»
 Î»= c/f
= 3 x 10\(^8\)
2.424 x 10\(^{15}\) Hz

(c) A: Natural radioactivity
B: Artificial radioactivity
Any correct difference



