Which of the following pairs are isoelectronic and isostructural?
$$NO_3^-$$, $$CO_3^{2-}$$, $$ClO_3^-$$, SO₃

Mixture X = 0.02 mol of [Co(NH₃)₅SO₄]Br and 0.02 mol of [Co(NH₃)₅Br]SO₄ was prepared in 2 litre of solution.
1 litre of mixture X + excess AgNO₃ $$ \to $$ Y.
1 litre of mixture X + excess BaCl₂ $$ \to $$ Z
No. of moles of Y and Z are

Which has maximum number of atoms?

If $$f\left( x \right) = \int\limits_{{x^2}}^{{x^2} + 1} {{e^{ - {t^2}}}} dt,$$ then $$f(x)$$ increases in