How many grams of concentrated nitric acid solution should be used to prepare $250 \ mL$ of $2.0 \ M \ HNO_3$? The concentrated acid is $70\% \ HNO_3$ by mass.

In the reaction $2 KClO_{3(s)} \longrightarrow 2 KCl_{(s)} + 3 O_{2(g)}$,$\Delta H^{\circ} = -78 \ kJ$. If $33.6 \ L$ of oxygen gas is liberated at $S.T.P.$,what is the mass of $KCl_{(s)}$ produced (in $g$)? (Atomic mass: $K = 39, Cl = 35.5 \ g \ mol^{-1}$)

How many grams of $NaOH$ will be required to prepare $250 \, mL$ of $0.1 \, M$ solution?

The density of a gas at $STP$ is $2.86 \, g \, L^{-1}$. Which of the following is the gas?

$20 \ mL$ of sodium iodide solution gave $4.74 \ g$ silver iodide when treated with excess of silver nitrate solution. The molarity of the sodium iodide solution is $........ M$. $(Nearest \ Integer \ value)$
$(Given: Na=23, I=127, Ag=108, N=14, O=16 \ g \ mol^{-1})$

One mole of magnesium nitride on the reaction with an excess of water gives