Bleaching powder is obtained by the action of chlorine on which of the following?

The gas produced by the passage of air over hot coke is

Identify the correct statement$(s)$ from the following: $I$. The catenation property of group $14$ elements decreases from carbon to tin. $II$. Fullerene $(C_{60})$ has $20$ five-membered carbon rings and $12$ six-membered carbon rings. $III$. $SiO_2$ is soluble in conc. $NaOH$.

Identify the correct statements among the following:
$a$) $C_{60}$ molecule has $12$ five-membered rings and $20$ six-membered rings.
$b$) $H_2CO_3 / HCO_3^-$ buffer system helps to maintain $pH$ of blood between $7.26$ and $7.42$.
$c$) Graphite is used as a dry lubricant in machines running at high temperatures.

Which of the following has the lowest melting point?

Which of the following statements is incorrect regarding zeolites?