Who is called the father of chemistry?

Identify the compound formed from elements $X, Y, Z$ having oxidation states $+2, +5, -2$ respectively.

In a $20\%$ aqueous solution of $H_2O_2$,the mole fraction of water is $.......$.

Which of the following has the highest mass?

When $800 \ mL$ of $0.5 \ M$ nitric acid is heated in a beaker,its volume is reduced to half and $11.5 \ g$ of nitric acid is evaporated. The molarity of the remaining nitric acid solution is $x \times 10^{-2} \ M$. (Nearest Integer) (Molar mass of nitric acid is $63 \ g \ mol^{-1}$)

The incorrect postulates of the Dalton's atomic theory are :
$A$. Atoms of different elements differ in mass.
$B$. Matter consists of divisible atoms.
$C$. Compounds are formed when atoms of different element combine in a fixed ratio.
$D$. All the atoms of given element have different properties including mass.
$E$. Chemical reactions involve reorganisation of atoms.
Choose the correct answer from the options given below :