The species Ar, K+ and Ca²⁺ contain the same
number of electrons. In which order do their radii
increase ?

The correct bond order in the following species is:-

"Metals are usually not found as nitrates in their
ores".
Out of the following two (a and b) reasons which
is/are true for the above observation ?
(a) Metal nitrates are highly unstable.
(b) Metal nitrates are highly soluble in water.

Bithional is generally added to the soaps as an
additive to function as a/an :-

The Ksp of Ag₂CrO₄, AgCl, AgBr and AgI are
respectively, 1.1 × 10^–12, 1.8 × 10^–10, 5.0 × 10^–13,
8.3 × 10^–17. Which one of the following salts will
precipitate last if AgNO3 solution is added to the
solution containing equal moles of NaCl, NaBr, NaI
and Na₂CrO₄ ?

 In Duma's method for estimation of nitrogen, 0.25
g of an organic compound gave 40 mL of nitrogen
collected at 300 K temperature and 725 mm pressure.
If the aqueous tension at 300 K is 25 mm, the
percentage of nitrogen in the compound is :-