What would happen when a solution of potassium chromate is treated with an excess of dilute nitric acid?

$A$ soft drink was bottled with a partial pressure of $CO_2$ of $3 \ bar$ over the liquid at room temperature. The partial pressure of $CO_2$ over the solution approaches a value of $30 \ bar$ when $44 \ g$ of $CO_2$ is dissolved in $1 \ kg$ of water at room temperature. The approximate $pH$ of the soft drink is............... $\times 10^{-1}$ (First dissociation constant of $H_2CO_3 = 4.0 \times 10^{-7}$; $\log 2 = 0.3$; density of the soft drink $= 1 \ g \ mL^{-1}$)

Statement $A$: $pH$ of a buffer increases with increasing temperature. Statement $B$: The value of $K_W$ of water decreases with decreasing temperature.

If the degree of dissociation of formic acid is $11.0 \%$,the molar conductivity of $0.02 \ M$ solution of it is (Given: $\lambda^{\circ}(H^{+}) = 349.6 \ S \ cm^2 \ mol^{-1}, \lambda^{\circ}(HCOO^{-}) = 54.6 \ S \ cm^2 \ mol^{-1}$)

For a $C \ M$ solution of a weak base $BOH$ having a van't Hoff factor '$i$',the base dissociation constant $K_b$ will be:

The pairs of compounds which cannot exist together in aqueous solution are :
$I. NaH_2PO_4$ and $Na_2CO_3$ $II. Na_2CO_3$ and $NaHCO_3$
$III. NaOH$ and $NaH_2PO_4$ $IV. NaHCO_3$ and $NaOH$