The strength of an aqueous $$ $\mathrm{N}\mathrm{a}\mathrm{O}\mathrm{H}$ solution is most accurately determined by titrating : (Note : consider that an appropriate indicator is used)

xCl₂+yOH^– <!-- [if gte mso 9]><xml> </xml><![endif]-->zCl^–+pClO^–

Balance the above reaction and find out values of x, y, z and p.

Which of the following is a disproportionation reaction?

A.  Cu⁺ <!-- [if gte mso 9]><xml> </xml><![endif]-->  $\stackrel{}{\to }$ Cu²⁺ + Cu

B.  <!-- [if gte mso 9]><xml> </xml><![endif]-->  <!-- [if gte mso 9]><xml> </xml><![endif]-->  <!-- [if gte mso 9]><xml> </xml><![endif]-->  $Mn{O}_4^{2-}$ $\stackrel{}{\to }$ $Mn{O}_4^{2-}$ + MnO₂

C.  H₂O₂ <!-- [if gte mso 9]><xml> </xml><![endif]-->  $\stackrel{}{\to }$ O₂ + H₂O

D.  <!-- [if gte mso 9]><xml> </xml><![endif]-->  <!-- [if gte mso 9]><xml> </xml><![endif]--> Cr^{3+ $Cr{O}_4^{2-}$ $\stackrel{}{\to }$} + H₂O

Statement-I: Potassium hydrogen phthalate is primary standard for NaOH solution.

Statement-II: Phenolphthalein is used to detect completion of titration.

(1) Both statement-l and statement-II are correct

(2) Statement-1 is correct and statement-II is incorrect

(3) Statement-l is incorrect and statement-II is correct

(4) Both statement-I and statement-II are incorrect

The number of moles of K₂Cr₂O₇ that will be needed to react with one mole of nitrite ion in acidic solution is

A metal ion M³⁺loses 3 electrons, its oxidation number will be