(A) The reaction of $MnO_2$ with $KOH$ and $KNO_3$ is: $MnO_2 + 2KOH + KNO_3 \to K_2MnO_4 + KNO_2 + H_2O$. The product $K_2MnO_4$ (potassium manganate

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(A) The reaction of $MnO_2$ with $KOH$ and $KNO_3$ is: $MnO_2 + 2KOH + KNO_3 \to K_2MnO_4 + KNO_2 + H_2O$. The product $K_2MnO_4$ (potassium manganate) is dark green in color. In an acidic medium,the manganate ion $(MnO_4^{2-})$ undergoes disproportionation: $3MnO_4^{2-} + 4H^+ \to 2MnO_4^- + MnO_2 + 2H_2O$. The $MnO_4^-$ (permanganate) ion is dark purple in color. Thus,$X$ is $Mn$.

Class 12 Chemistry The d- and f-Block Elements Compounds of Transitional elements

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When $XO_2$ is fused with an alkali metal hydroxide in the presence of an oxidizing agent such as $KNO_3$,a dark green product is formed which disproportionates in an acidic solution to afford a dark purple solution. $X$ is

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A
$Mn$
B
$Cr$
C
$V$
D
$Ti$

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The d- and f-Block Elements

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Compounds of Transitional elements

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When $XO_2$ is fused with an alkali metal hydroxide in the presence of an oxidizing agent such as $KNO_3$,a dark green product is formed which disproportionates in an acidic solution to afford a dark purple solution. $X$ is

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Which of the following is incorrect about $K_{2}Cr_{2}O_{7}$?

Name the oxometal anions of the first series of the transition metals in which the metal exhibits the oxidation state equal to its group number.

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Identify the correct $(T)$ and incorrect $(F)$ statements from the following:
$(a)$ $MnO_4^{2-}$ is diamagnetic.
$(b)$ $MnO_4^-$ is green and $MnO_4^{2-}$ is purple.
$(c)$ $K_2Cr_2O_7$ is yellow.
$(d)$ $K_2Cr_2O_7$ is orange.