List of top Chemistry Questions on Molecular & Empirical Formula

5.4 g of a metal (M) reacts with chlorine to form \(26.7\,\text{g}\) of metal chloride. What is the weight (in g) of M that reacts with \(48\,\text{g}\) of oxygen?

1.5 g of an organic compound was analysed by Kjeldahl's method for estimation of nitrogen. The ammonia liberated was passed into 30 mL of 1N HCl solution. The remaining HCl was further neutralised by 120 mL of N/10 NaOH solution. The percentage of nitrogen in the compound is:

0.42 g of an organic compound containing C, H and O gave on combustion 0.942 g of $CO_2$ and 0.231 g of $H_2O$. The empirical formula weight of the compound is (At.wt: $C=12$ u, $H=1$ u, $O=16$ u)

What volume of hydrogen gas at STP would be liberated by action of 50 mL of $H_2SO_4$ of 50% purity (density $= 1.3 \text{ g mL}^{-1}$) on 20 g of zinc?
Given : Molar mass of H, O, S, Zn are 1, 16, 32, 65 $\text{g mol}^{-1}$ respectively.

Which of the following contain the same number of atoms? (Given : Molar mass in g mol\(^{-1}\) of H, He, O and S are \(1,4,16\) and \(32\) respectively)}

• [A.] \(2\,\text{g}\) of \(O_2\) gas
• [B.] \(4\,\text{g}\) of \(SO_2\) gas
• [C.] \(1400\,\text{mL}\) of \(O_2\) at STP
• [D.] \(0.05\,\text{L}\) of He at STP
• [E.] \(0.0625\,\text{mol}\) of \(H_2\) gas

Choose the correct answer from the options given below:

An organic compound has the empirical formula CH$_2$O. Its vapour density is 45. The molecular formula of compound is

36 g of A reacts with 54 g of B to form AB\(_2\), if the molar mass of A and B is respectively 60 and 80, then choose the correct option from the following.

Consider the following data: \[ \text{Na(s)} + \frac{1}{2} \text{Cl}_2 \text{(g)} \rightarrow \text{NaCl(s)} \quad \Delta H^\circ = -411 \, \text{kJ/mole} \] \[ \text{Na(s)} \rightarrow \text{Na(g)} \quad \Delta H^\circ = 107 \, \text{kJ/mole} \] \[ \text{Cl}_2 \text{(g)} \rightarrow 2\text{Cl}(g) \quad \Delta H^\circ = 242 \, \text{kJ/mole} \] \[ \text{Cl(g)} + e^- \rightarrow \text{Cl}^-(g) \quad \Delta H^\circ = -355 \, \text{kJ/mole} \] \[ \text{Na(g)} \rightarrow \text{Na}^+(g) + e^- \quad \Delta H^\circ = 502 \, \text{kJ/mole} \] Find the lattice energy of NaCl(s).

Consider the statements below: Statement I: BCl\(_3\) is covalent in nature. Statement II: BCl\(_3\) undergoes hydrolysis to form [B(OH)\(_4\)]\(^{+}\) and BH\(_2^{+}\). In the light of the above statements, choose the correct option.

What is the total number of moles of 'C' atoms and 'H' atoms respectively present in following n mole molecule?

Which of the following statements is NOT correct regarding voids in lattice structure?

Calculate the number of \(\text{Cl}^-\) ions in 222 g unhydrous calcium chloride?
(At. mass \(\text{Ca} = 40, \text{Cl} = 35.5\) )

Which of the following statements is NOT correct regarding voids in lattice structure?

On complete combustion 1.0 g of an organic compound (X) gave 1.46 g of CO₂ and 0.567 g of H₂O. The empirical formula mass of compound (X) is:
(Given molar mass in g mol\(^{-1}\): C: 12, H: 1, O: 16)

An organic compound contains carbon = 38.71%, Hydrogen = 9.67% and Oxygen. The empirical formula of the compound would be: