Mole Concept Questions

Among the following, choose the ones with equal number of atoms:A. $212\text{g}$ of ${\text{Na}}_2{\text{CO}}_3$ ($\text{s}$) [molar mass = $106\text{g}$ ]B. $248\text{g}$ of ${\text{Na}}_2\text{O}$ ($\text{s}$) [molar mass = $62\text{g}$ ]C. $240\text{g}$ of $\text{NaOH}$ ($\text{s}$) [molar mass = $40\text{g}$ ]D. $12\text{g}$ of ${\text{H}}_2$ ($\text{g}$) [molar mass = $2\text{g}$ ]E. $220\text{g}$ of ${\text{CO}}_2$ ($\text{g}$) [molar mass = $44\text{g}$ ]Choose the correct answer from the options given below:

What volume of oxygen gas (${\text{O}}_2$) measured at $0^{\circ }\text{C}$ and $1\text{atm}$, is needed to burn completely $1\text{L}$ of propane gas (${\text{C}}_3{\text{H}}_8$) measured under the same conditions?

How many moles of lead (II) chloride will be formed from a reaction between $6.5\text{g}$ of $\text{PbO}$ and $3.2\text{g}$ of $\text{HCl}$?

Volume occupied by one molecule of water (density $=1{\text{g cm}}^{-3}$) is:

$10\text{g}$ of hydrogen and $64\text{g}$ of oxygen were filled in a steel vessel and exploded. Amount of water produced in this reaction will be:

$25.3\text{g}$ of sodium carbonate, ${\text{Na}}_2{\text{CO}}_3$ is dissolved in enough water to make $250\text{mL}$ of solution. If sodium carbonate dissociates completely, molar concentration of sodium ion, ${\text{Na}}^{+}$ and carbonate ions, ${\text{CO}}_3^{2-}$ are respectively: (Molar mass of ${\text{Na}}_2{\text{CO}}_3=106{\text{g mol}}^{-1}$)

The number of atoms in $0.1\text{mol}$ of a triatomic gas is ($N_A=6.02\times 10^{23}{\text{mol}}^{-1}$):

Which has the maximum number of molecules among the following?

How many grams of concentrated nitric acid solution (70% ${\text{HNO}}_3$ by mass) should be used to prepare $250\text{mL}$ of $2.0\text{M}$ ${\text{HNO}}_3$?

$6.02\times 10^{20}$ molecules of urea are present in $100\text{mL}$ of its solution. The concentration of the solution is:

When $22.4\text{litres}$ of ${\text{H}}_2(g)$ is mixed with $11.2\text{litres}$ of ${\text{Cl}}_2(g)$, each at S.T.P., the moles of $\text{HCl}(g)$ formed is equal to:

$1.0\text{g}$ of magnesium is burnt with $0.56\text{g}$ ${\text{O}}_2$ in a closed vessel. Which reactant is left in excess and by how much? (At. wt. $\text{Mg}=24;\text{O}=16$)

The number of water molecules is maximum in:

If Avogadro number $N_A$, is changed from $6.022\times 10^{23}{\text{mol}}^{-1}$ to $6.022\times 10^{20}{\text{mol}}^{-1}$, this would change:

$20.0\text{g}$ of a magnesium carbonate sample decomposes on heating to give carbon dioxide and $8.0\text{g}$ magnesium oxide. What will be the percentage purity of magnesium carbonate in the sample? (Atomic weight: $\text{Mg}=24$, $\text{C}=12$, $\text{O}=16$)

What is the mass of the precipitate formed when $50\text{mL}$ of $16.9\%$ solution of ${\text{AgNO}}_3$ is mixed with $50\text{mL}$ of $5.8\%$ $\text{NaCl}$ solution?