(a)(i) State Pauli's exclusion principle: Pauli's exclusion principle states that two electrons in the same orbita of an atom cannot have same values for all four quantum numbers/no two electrons can have the same four quantum numbers/no two electrons in the same orbital if an atom can have the same spin.
(ii) Hund's rule of maximum multiplicity. Hund's rule states that electrons occupy each orbital supply first before pairinc takes place in degenerate orbital/most stable arrangement of electrons in sunshells is the one with the greatest number of parallel spins.

(b)(i) (a) Cu\(^+\) — 1s\(^2\)2s\(^2\)2P\(^6\)3P\(^6\)3d\(^{10}\)
(b) Cu\(^{2+}\) --- 1s\(^2\)2s\(^2\)2P\(^6\)3s\(^2\)3P\(^6\)3d\(^9\)

(ii) i. Cu\(^+\) — no unpaired electron
ii. Cu\(^{2+}\) — one unpaired electron
iii. Redox/disproportional
iv. Cu\(_2\)O / CuCI / Cu\(_2\)Cl\(_2\)

(c)(i) (a) gamma rays (b) alpha particles
(ii) (a) gamma (y) - No charge/electrically neutral. (b) alpha \(\alpha\)- positively charge.
(iii) (i) Nuclear fusion (2) Nuclear fusion (3) half-life.

(d) (i) Li\(^+\), Na\(^+\), K\(^+\), size increase down a group as more shells are being added.
(ii) F, O\(^{2-}\), N\(^{2-}\), size increase as nuclear charge decrease in the same period/isoelectronic.

(e) Phosphorus (V) oxide = P\(_{4}\)O\(_{10}\)/P\(_{2}\)Q\(_{5}\)
= (31 x 4) + (16 x 10) or (31 x 2) + (16 x 5) = 124 + 160 or 62 + 80 = 284 or 142.
Therefore % by mass of phosphorus = \(\frac{4P}{P_4Q_{10}}\) x 100% or
\(\frac{2P}{P_2Q_{5}}\) x 100%
\(\frac{124}{284}\) x 100% or \(\frac{62}{142}\) x 100%
= 43.7%
or 100 - 43.7 = 56.3% oxygen.