$(v)$ In figure $5 , sp$ hybridised carbon is more electronegative. -ve charge on more electronegative atom makes it more stable. [ref. image]

Also, there is $-I$ effect.

$\therefore$ It is most stable.

$(iii)$ $H - C \equiv \overline{ C }$

sp hybridized carbon carry -ve charge.

$\therefore$ Hence, it is also more stable

$(ii)$ In figure $2$, resonance is taking place. [ref. image]

$\therefore$ It is more stable.

$(iv)$ $\overline{ C } H _3$

-ve charge is carried by $sp ^3$ hybridised carbon.

$\therefore$ It is less stable.

$(i)$ In figure $1$ , the central $C$ is surrounded by $CH _3$ and hence it shows $+ I$ effect from $3$ sides. [ref. image]

$\therefore$ Hence, it is least stable.

$\therefore \text { (v) }\,<\,\text { (iii) }\,<\,\text { (ii) }\,<\,\text { (iv) }\,<\,\text { (i) }$