For the four successive transition elements $(Cr, Mn, Fe, \text{ and } Co)$,the stability of $+2$ oxidation state will be in which of the following order?
(Atomic numbers: $Cr = 24, Mn = 25, Fe = 26, Co = 27$)

Ferrous sulphate on heating gives

In the human body,if necessary,the plates,screws,or wires used for surgery are made up of:

Identify the statements which are not correct.
$i$. $CrO_3$ and $Mn_2O_7$ are basic oxides
$ii$. $V_2O_3$ and $V_2O_4$ are acidic oxides
$iii$. $Cr(VI)$ is more stable than $W(VI)$

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 metal cation oxides is not amphoteric?