In the preparation of baking soda,what is the ratio of $H_2O$ and $CO_2$ used to react with $Na_2CO_3$ to form $NaHCO_3$?

Which of the following equations is written incorrectly?

$1.0 \ g$ of magnesium is burnt with $0.56 \ g \ O_2$ in a closed vessel. Which reactant is left in excess and how much? (At. $wt. \ Mg = 24, O = 16$)

When $400 \ mL$ of $0.2 \ M \ H_2SO_4$ solution is mixed with $600 \ mL$ of $0.1 \ M \ NaOH$ solution,the increase in temperature of the final solution is $...... \times 10^{-2} \ K$. (Round off to the Nearest Integer).
$\left[ \text{Use } : H^{+}_{(aq)} + OH^{-}_{(aq)} \rightarrow H_2O : \Delta_{r}H = -57.1 \ kJ \ mol^{-1} \right]$
Specific heat of $H_2O = 4.18 \ J \ K^{-1} \ g^{-1}$
Density of $H_2O = 1.0 \ g \ cm^{-3}$
Assume no change in volume of solution on mixing.

Combustion of $50 \ mL$ methane is carried out with $150 \ mL$ of air containing $21 \%$ oxygen by volume. What will be the total volume of the gaseous mixture after the reaction? (Assume water is in the gaseous state and air contains $79 \%$ nitrogen by volume).
$CH_{4(g)} + 2O_{2(g)} \to CO_{2(g)} + 2H_2O_{(g)}$

$56 \ g$ of $CaO$ has been mixed with $63 \ g$ of $HNO_3$. The amount of $Ca(NO_3)_2$ formed is: (in $g$)