The option(s) in which at least three molecules follow Octet Rule is(are)

Option A: \(\mathrm{CO}_2, \mathrm{C}_2 \mathrm{H}_4, \mathrm{NO}\) and HCl
1. \(\mathrm{CO}_2\) : Carbon dioxide follows the octet rule. Carbon forms double bonds with two oxygen atoms, allowing it to have 8 electrons in its valence shell.
2. \(\mathrm{C}_2 \mathrm{H}_4\) : Ethylene follows the octet rule. Each carbon forms a double bond with the other carbon and single bonds with two hydrogen atoms, resulting in 8 electrons in the valence shell of the carbons.
3. NO: Nitric oxide does not follow the octet rule. It has an odd number of electrons, making it a free radical.
4. HCl: Hydrogen chloride follows the octet rule. Chlorine has 8 electrons in its valence shell when bonded with hydrogen.
Thus, three molecules \(\mathrm{CO}_2, \mathrm{C}_2 \mathrm{H}_4\), and HCl follow the octet rule here.
Option B: \(\mathrm{NO}_2, \mathrm{O}_3, \mathrm{HCl}\) and \(\mathrm{H}_2 \mathrm{SO}_4\)
1. \(\mathrm{NO}_2\) : Nitrogen dioxide does not follow the octet rule. It has an odd number of electrons.
2. \(\mathrm{O}_3\) : Ozone follows the octet rule. It has a resonance structure that allows each oxygen atom to have 8 electrons in its valence shell.
3. HCl: As mentioned, hydrogen chloride follows the octet rule.
4. \(\mathrm{H}_2 \mathrm{SO}_4\) : Sulfuric acid follows the octet rule. All atoms achieve stable configurations through bonding.
Thus, three molecules \(\mathrm{O}_3, \mathrm{HCl}\), and \(\mathrm{H}_2 \mathrm{SO}_4\) follow the octet rule in this option.
Option C: \(\mathrm{BCl}_3, \mathrm{NO}_2, \mathrm{NO}_2\) and \(\mathrm{H}_2 \mathrm{SO}_4\)
1. \(\mathrm{BCl}_3\) : Boron trichloride does not follow the octet rule. Boron has only 6 electrons in its valence shell.
2. NO: As mentioned, nitric oxide does not follow the octet rule.
3. \(\mathrm{NO}_2\) : As mentioned, nitrogen dioxide does not follow the octet rule.
4. \(\mathrm{H}_2 \mathrm{SO}_4\) : Sulfuric acid follows the octet rule.
Thus, only one molecule, \(\mathrm{H}_2 \mathrm{SO}_4\). follows the octet rule in this option.
Option D: \(\mathrm{CO}_2, \mathrm{BCl}_3, \mathrm{O}_3\) and \(\mathrm{C}_2 \mathrm{H}_4\)
1. \(\mathrm{CO}_2\) : As mentioned, carbon dioxide follows the octet rule.
2. \(\mathrm{BCl}_3\) : As mentioned, boron trichloride does not follow the octet rule.
3. \(\mathrm{O}_3\) : As mentioned, ozone follows the octet rule.
4. \(\mathrm{C}_2 \mathrm{H}_4\) : As mentioned, ethylene follows the octet rule.
Thus, three molecules \(\mathrm{CO}_2, \mathrm{O}_3\), and \(\mathrm{C}_2 \mathrm{H}_4\) follow the octet rule in this option.
Conclusion: The correct options are Option A and Option D, both having at least three molecules that follow the octet rule.