In the thermal decomposition of a metal carbonate,the oxidation state of the metal changes if the metal is

Assertion : When a metal is treated with conc. $HNO_3$,it generally yields a nitrate,$NO_2$,and $H_2O$.
Reason : Conc. $HNO_3$ reacts with a metal and first produces a metal nitrate and nascent hydrogen. The nascent hydrogen then further reduces $HNO_3$ to $NO_2$.

For the reaction $P_4 + xOH^- + yH_2O \to PH_3 + H_2PO_2^-$,determine the correct relationship between $x$ and $y$.

Balance the redox reaction where $Fe^{+2}$ in an acidic medium reduces $Cr_2O_7^{-2}$ ion to $Cr^{+3}$ ion,while $Fe^{+2}$ itself is oxidized to $Fe^{+3}$.

In the reaction of sodium thiosulphate with $I_2$ in aqueous medium, the equivalent weight of sodium thiosulphate is equal to:

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$Ba(N_3)_2 \xrightarrow{\Delta} Ba + 3N_2 \uparrow$