When $Cu^{2+}$ ion is treated with $KI$,a white precipitate is formed. Explain the reaction with the help of a chemical equation.

How many statements are incorrect?
$(a)$ $Mn^{+3}$ and $Co^{+3}$ are strong oxidising agents.
$(b)$ $Ti^{+2}$,$V^{+2}$ and $Cr^{+2}$ are strong reducing agents.
$(c)$ $CrO_3$ is acidic in nature.
$(d)$ $E^{\circ}_{M^{+3}/M^{+2}} = -ve$ for $Fe$.

Which of the following statements are correct?
$A$. The $M^{3+}/M^{2+}$ reduction potential for iron is greater than manganese.
$B$. The higher oxidation states of first row $d$-block elements get stabilized by oxide ion.
$C$. Aqueous solution of $Cr^{2+}$ can liberate hydrogen from dilute acid.
$D$. Magnetic moment of $V^{2+}$ is observed between $4.4-5.2 \ BM$.
Choose the correct answer from the options given below:

Which of the following ions can reduce dilute acid to give hydrogen gas?

$E^{\circ}_{M^{3+} \mid M^{2+}} \text{ (in } V\text{) is highest for}$

Which of these statements is not true?