When $800 \ mL$ of $0.5 \ M$ nitric acid is heated in a beaker,its volume is reduced to half and $11.5 \ g$ of nitric acid is evaporated. The molarity of the remaining nitric acid solution is $x \times 10^{-2} \ M$. (Nearest Integer) (Molar mass of nitric acid is $63 \ g \ mol^{-1}$)

$K_2CS_3$ can be called potassium:

When a standard solution of $NaOH$ is left in air for a few hours:

Fill in the blanks given below:
$(i)$ The mass of $1$ mole of a substance expressed in grams is called its .........
$(ii)$ The amount of solute dissolved in $1$ $kg$ of solvent is called its .........
$(iii)$ The Fahrenheit scale in a thermometer is marked between .........
$(iv)$ In $NaCl$,each $Na^{+}$ ion is surrounded by ......... $Cl^{-}$ ions.

The more commonly used baking powder contains about $30\%$ $NaHCO_3$,$20\%$ $NaAl(SO_4)_2$,$10\%$ $Ca(H_2PO_4)_2$ and $40\%$ starch. Which of the following statements is/are correct?

$A$ mixture of sodium oxide $(Na_2O)$ and calcium oxide $(CaO)$ is dissolved in water and saturated with excess carbon dioxide $(CO_2)$ gas. The resulting solution is $......$ It contains $.........$ :