JEE Main 2017 · 8 Apr · Shift 1 · Chemistry Q42

← JEE Main 2017 · 8 Apr · Shift 1

ChemistrySingle correct+4 / -1Question 42 of 90

The pair of compounds having metals in their highest oxidation state is :

\ce{MnO2}

and

\ce{CrO2Cl2}

\ce{[NiCl4]^2-}

and

\ce{[CoCl4]^2-}

\ce{[Fe(CN)6]^3-}

and

\ce{[Cu(CN)4]^2-}

\ce{[FeCl4]-}

and

\ce{Co2O3}

Answer and worked solution

Official answer: Bonus: full marks to everyone

The oxidation states are:

Mn +4 in $\ce{MnO2}$ , Cr +6 in $\ce{CrO2Cl2}$ ;
Ni +2 and Co +2;
Fe +3 and Cu +2;
Fe +3 and Co +3.

No pair has both metals in their highest oxidation state: manganese reaches +7, nickel and cobalt go beyond +2, iron reaches +6. Which pair counts depends on whether "highest" means the highest possible or the highest common state, and the question was given marks to all.

Topics:Transition element properties Oxidation number

← Previous question Next question →

JEE Main 2017 · 8 Apr · Shift 1, Chemistry question 42