$Zn$ and $Hg$ belong to the same group,but they differ in many of their properties. The property that is shared by both is

Iron is rendered passive by treatment with

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 one of the following oxides is ionic?

Which of the following compounds reacts with $NaOH$ and $Na_2O_2$ to produce a yellow color?

The nature of oxides $V_{2}O_{3}$ and $CrO$ is indexed as '$X$' and '$Y$' type respectively. The correct set of $X$ and $Y$ is: