Which of the following oxides is most acidic in nature?

How many of the following oxides are amphoteric?
$BeO, ZnO, Sb_2O_3, CO, CaO, SO_2, SO_3$

When a metal is burnt in air,the resulting ash,upon moistening,gives the smell of $NH_3$. Which metal is it?

$Ba$,$Ca$,and $Sr$ form halide hydrates. Their formulas are $BaCl_2 \cdot x H_2 O$,$CaCl_2 \cdot y H_2 O$,and $SrCl_2 \cdot z H_2 O$. The values of $x$,$y$,and $z$ respectively are:

Observe the following reactions:
$Dimer \longleftarrow \text{Vapour phase } MCl_2 \xrightarrow{1200 \ K} \text{linear monomer}$.
What is $M$?

Match the following:

List-$I$	List-$II$
$I$. $CaSO_4 \cdot 2H_2O$	$A$. Knee cement
$II$. $CaSO_4 \cdot 0.5H_2O$	$B$. Gypsum
$III$. $CaSO_4$	$C$. Plaster of Paris
	$D$. Dead burnt plaster