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

Who is called the father of chemistry?

At $300 \ K$ temperature,$20 \ g \ H_2$,$220 \ g \ CO_2$,and $140 \ g \ N_2$ are filled in a vessel having volume $2 \ L$. Find the total pressure in $bar$ unit and which gas is removed from the vessel so that pressure can be reduced by $50 \%$. $(R = 8.34 \times 10^{-2} \ L \ bar \ K^{-1} \ mol^{-1})$

Mohr's salt is

The number of electrons in one molecule of urea $(NH_2CONH_2)$ is

$A$ metal oxide contains $75 \%$ metal by mass. If the vapour density of the metal chloride is $89$,what is the atomic weight of the metal?