The amphoteric oxide of Vanadium $(V)$ is $V_2O_5$. It reacts with alkali to form an oxoion '$X$' and with acid to form an oxoion '$Y$'. The oxidation states of '$V$' in '$X$' and '$Y$' are respectively:

When a chromite ore $(A)$ is fused with sodium carbonate in free excess of air and the product is dissolved in water,a yellow solution of compound $(B)$ is obtained. After treatment of this yellow solution with sulphuric acid,compound $(C)$ can be crystallised from the solution. When compound $(C)$ is treated with $KCl$,orange crystals of compound $(D)$ crystallise out. Identify $A$ to $D$ and also explain the reactions.

Potassium manganate $(K_2MnO_4)$ is not formed in which of the following reactions?

Which compounds are formed when $Mn_2O_7$ and $CrO_3$ react with water,given that they are acidic in nature?

Fill in the blanks:
$(1)$ In the dichromate ion,the $O-Cr-O$ bond angle is ....... $^o$.
$(2)$ The reaction $3Sn^{2+} \to 3Sn^{4+} + 6e^-$ occurs via .........,in which $Sn^{2+}$ is ......... .
$(3)$ The symbols for stannous and stannic are ......... and ......... respectively.
$(4)$ $V_2O_4$ dissolves in acidic compounds to give ......... salts.

Silver nitrate is mainly used