The decreasing order of stability of ${\mathrm{O}}_2,{\mathrm{O}}_2^{-},{\mathrm{O}}_2^{+}$ $\mathrm{and}$ ${\mathrm{O}}_2^{2-}$is: 

1. ${\mathrm{O}}_2^{+}>{\mathrm{O}}_2>{\mathrm{O}}_2^{-}>{\mathrm{O}}_2^{2-}$

2. ${\mathrm{O}}_2^{2-}>{\mathrm{O}}_2^{-}>{\mathrm{O}}_2>{\mathrm{O}}_2^{+}$

3. ${\mathrm{O}}_2>{\mathrm{O}}_2^{+}>{\mathrm{O}}_2^{2-}>{\mathrm{O}}_2^{-}$

4. ${\mathrm{O}}_2^{-}>{\mathrm{O}}_2^{2-}>{\mathrm{O}}_2^{+}>{\mathrm{O}}_2$

The correct statement regarding defects in a crystalline solid is:

Which one of the following statements is not correct for a nucleophile?

1. Nucleophile is a lewis acid.
2. Ammonia is a nucleophile.
3. Nucleophiles attack low electron density sites.
4. Nucleophiles are not electron-seeking.

The hybridization involved in the complex ${\left[\mathrm{Ni}{\left(\mathrm{CN}\right)}_4\right]}^{2-}$is:
(Atomic number of Ni=28)

The sum of the coordination number and oxidation number of the metal M in the complex [M(en)₂(C₂O₄)]Cl is:

Which of the statements given below is incorrect?

1. \(\mathrm{C l_{2} O_{7  }}\)${}_{}$is an anhydride of perchloric acid
2. \(\mathrm{O_{3}}\)${\mathrm{}}_{}$ molecule is bent
3. ONF is isoelectronic with \(\mathrm{N O_{2}^{-}}\)${}_{}^{}$ 
4. \(\mathrm{O F_{2}}\) is an oxide of fluorine

In the extraction of copper from its sulphide ore, the metal is finally obtained by the reduction of cuprous oxide with?

1. Iron(II) sulphide

2. Carbon monoxide

3. Copper(I) sulphide

4. Sulphur dioxide

Which one of the following pairs of solutions is not an acidic buffer?

1. ${\mathrm{HClO}}_4$ $\mathrm{and}$ ${\mathrm{NaClO}}_4$
2. ${\mathrm{CH}}_3\mathrm{COOH}$ $\mathrm{and}$ ${\mathrm{CH}}_3\mathrm{COONa}$
3. ${\mathrm{H}}_2{\mathrm{CO}}_3$ $\mathrm{and}$ ${\mathrm{Na}}_2{\mathrm{CO}}_3$
4. ${\mathrm{H}}_3{\mathrm{PO}}_4$ $\mathrm{and}$ ${\mathrm{Na}}_3{\mathrm{PO}}_4$

Assuming complete ionization, same moles of which of the following compounds will require the least amount of acidified KMnO₄ for complex oxidation?

1. $FeS{O}_4$

2. $FeS{O}_3$

3. $Fe{C}_2{O}_4$

4. $Fe{\left(N{O}_2\right)}_2$