Which of the following elements reacts with water?

Assertion : $PbCl_2$ is more stable than $PbCl_4$.
Reason : $PbCl_4$ is a powerful oxidising agent.

How is dry ice produced? Mention its uses.

Carbon monoxide gas is more dangerous than carbon dioxide gas. Why?

With respect to graphite and diamond,which of the statement$(s)$ given below is (are) correct?
$(A)$ Graphite is harder than diamond.
$(B)$ Graphite has higher electrical conductivity than diamond.
$(C)$ Graphite has higher thermal conductivity than diamond.
$(D)$ Graphite has higher $C-C$ bond order than diamond.

$Ge(II)$ compounds are strong reducing agents,whereas $Pb(IV)$ compounds are strong oxidizing agents. This is due to.........