(a)(i) Electronegatively, ionisation energy, electron affinity.
(ii)

Chemical reaction	Nuclear reaction
- Involves only the electron	- Involves the nucleus
- Not usually accompanied by great heat change	- Usually accompanied by a lot of heat change
- New elements are not formed	- New elements are formed
- External factors such as pressure, temperature and catalyst affect the rate of reaction.	- Not affected by external factors

(i) P and S are isotopes of the same element.

(ii) R contains 18 neutrons
(iii) T is chemically unreactive
(iv) Q readily

(b)

Atom of elements	P	Q	R	S	T
Mass number	16	40	35	18	20
Atom number	8	20	17	8	10

(I) P and S are isotopes of the same elements
(ii) R contains 18 neutrons
(iii) T is chemically unreactive
(iv) Q readily forms an ion with two positive charges
(v) R attains an octet structure by accepting one electron
(vi) Q forms an ionic bond with R
(vii) Q belongs to the s - block in the periodic table

(c)(i) To convert CuCO\(_3\) to Cu, heat strongly ; CuCO\(_3\) -> CuO + CO\(_2\) . Pass hydrogen over heated residue of CuO. H\(_2\) + CuO ---> Cu + H\(_2\)O
or pass NH\(_3\) over heated copper II oxide. 2CuO + 3NH\(_3\) —› 3Cu + 3H\(_2\)O + N\(_2\)

OR add dilute mineral acid to CuCO\(_3\) to form soluble salt: CuCO\(_3\) + 2HCI -> CuCl\(_2\) + H\(_2\) O + CO\(_2\) . Electrolysis using platinum electrodes or any inert electrode. Equation at the cathode Cu\(^{2+}\) + 2e\(^-\) \(\to\) Cu

OR add mineral acid to CuCO\(_3\) to form soluble salt CuCO + 2HCI -> CuCl\(_2\) + H\(_2\)O+ CO\(_2\) then add reactive metal e.g. Zinc or Aluminium CuCl\(_2\) + Zn -> Cu + ZnCl\(_2\)

(ii) To convert MgO to Mg\(_2\)SO\(_4\) , acid dilute H\(_2\)SO\(_4\) to excess MgO, filter off excess MgO. The filtrate is MgSO\(_4\) , MgO + H\(_2\)SO\(_4\) -> MgSO\(_4\) + H\(_2\)O. Evaporate / heat to dryness to obtain MgSO\(_4\).