What is 'plumbo solvency' referring to in the context of lead?

What is plumbosolvency,the dissolution of lead in?

Which of the following statements does not define the characteristic property of water,"Water is a universal solvent"?

In the following reaction,identify the nature of the product formed by the complete hydrolysis of the underlined atom at $R.T$.: $Na\underline{H} + H_2O \longrightarrow NaOH + H_2 \uparrow$

When chlorine water is exposed to sunlight,$O_2$ is liberated. Hence

Match List-$I$ with List-$II$ and select the correct answer using the codes given below.

List-$I$	List-$II$
$1.$ Heavy water	$(a)$ Bicarbonates of $Ca$ and $Mg$ in water
$2.$ Temporary hard water	$(b)$ No foreign ions in water
$3.$ Soft water	$(c)$ $D_2O$
$4.$ Permanent hard water	$(d)$ Sulphates and chlorides of $Ca$ and $Mg$ in water