First group element with highest boiling point is

A) Atomic radius…Li<Na<K<Rb<Cs;

B)IP₁…..Li>Na>K>Rb>Cs;

C) EN…..Li>Na>K>Rb>Cs;

D) MP…Li>Na>K>Rb>Cs;

E) BP…Li>Na>K>Rb>Cs;

F) Hardness, Metallic bond strength….Li>Na>K>Rb>Cs;

G) Metallic character….Li<Na<K<Rb<Cs;

H) Density…..Li<K<Na<Rb<Cs;

     Due larger inter atomic distances available vacant orbitals Potassium is less denser than Sodium.

I) Abundance in Earth's crust….Na>K>Rb>Li>Cs;

J) Hydration Enthalpy….Li⁺>Na⁺>K⁺>Rb⁺>Cs⁺

Thus ionic size in aqueous solution…..Li⁺>Na⁺>K⁺>Rb⁺>Cs⁺

Thus ionic mobility in aqueous solution…..Li⁺<Na⁺<K⁺<Rb⁺<Cs⁺ 

but ionic mobility in fused state ……Li⁺>Na⁺>K⁺>Rb⁺>Cs⁺

K) ${\mathrm{E}}_{{\mathrm{M}}^{+}/\mathrm{M}}^{°}$ values are negative.

Most negative for Li and least negative for Na.

${\mathrm{E}}_{{\mathrm{Li}}^{+}/\mathrm{Li}}^{°}\left(\mathrm{most} \mathrm{negative}\right)<{\mathrm{E}}_{{\mathrm{Cs}}^{+}/\mathrm{Cs}}^{°}<{\mathrm{E}}_{{\mathrm{Rb}}^{+}/\mathrm{Rb}}^{°}<{\mathrm{E}}_{{\mathrm{K}}^{+}/\mathrm{K}}^{°}<{\mathrm{E}}_{{\mathrm{Na}}^{+}/\mathrm{Na}}^{°}\left(\mathrm{least} \mathrm{negative}\right)$

Best reducing agent is Lithium, best oxidant is Na⁺;