Question

Choose the molecular compound only, from the following: \[ A.\ \mathrm{KI} \] \[ B.\ \mathrm{H_2O_2} \] \[ C.\ \mathrm{CHCl_3} \] \[ D.\ \mathrm{Li_2CO_3} \] Choose the correct answer from the options given below:
• A, B & C Only
• B & C Only
• B, C & D Only
• A, B & D Only

• A. A, B & C Only
• B. B & C Only
• C. B, C & D Only
• D. A, B & D Only

Hint:

Molecular compounds are usually formed between non-metals through covalent bonding. Examples: \[ \mathrm{H_2O,\ CO_2,\ CHCl_3} \] Metal + non-metal combinations are generally ionic.

Answer 1

The Correct Option is B

Concept: Compounds are generally classified into:
• Ionic compounds
• Molecular (covalent) compounds Ionic compounds:
• Formed by transfer of electrons.
• Usually formed between metals and non-metals.
• Exist as ions. Molecular compounds:
• Formed by sharing of electrons.
• Usually formed between non-metals.
• Exist as discrete molecules.

Step 1: Examine compound A: \( \mathrm{KI} \) Potassium iodide contains:
• Potassium (\(K\)) = metal
• Iodine (\(I\)) = non-metal Potassium loses one electron: \[ \mathrm{K \rightarrow K^+ + e^-} \] Iodine gains one electron: \[ \mathrm{I + e^- \rightarrow I^-} \] Thus: \[ \mathrm{KI = K^+I^-} \] This is an ionic compound, not a molecular compound. Hence: \[ \boxed{\mathrm{KI \ is\ not\ molecular}} \]

Step 2: Examine compound B: \( \mathrm{H_2O_2} \) Hydrogen peroxide contains:
• Hydrogen = non-metal
• Oxygen = non-metal The atoms share electrons through covalent bonding. Structure contains: \[ \mathrm{H-O-O-H} \] Therefore: \[ \boxed{\mathrm{H_2O_2 \ is\ a\ molecular\ compound}} \]

Step 3: Examine compound C: \( \mathrm{CHCl_3} \) Chloroform contains:
• Carbon
• Hydrogen
• Chlorine All are non-metals. Atoms are connected through covalent bonds. Hence: \[ \boxed{\mathrm{CHCl_3 \ is\ a\ molecular\ compound}} \]

Step 4: Examine compound D: \( \mathrm{Li_2CO_3} \) Lithium carbonate contains:
• Lithium ion \( \mathrm{Li^+} \)
• Carbonate ion \( \mathrm{CO_3^{2-}} \) The compound exists as ions: \[ \mathrm{2Li^+ + CO_3^{2-}} \] Thus it is predominantly ionic. Therefore: \[ \boxed{\mathrm{Li_2CO_3 \ is\ not\ molecular}} \]

Step 5: Identify molecular compounds only. The molecular compounds are: \[ \boxed{ \mathrm{H_2O_2 \ and \ CHCl_3} } \] That is: \[ \boxed{ B \ \&\ C\ \text{Only} } \]

Step 6: Match with the options. The correct option is: \[ \boxed{(2)} \] Additional Understanding: Molecular compounds usually:
• Have low melting points
• Poorly conduct electricity
• Exist as individual molecules Ionic compounds:
• Have high melting points
• Conduct electricity in molten state
• Exist as ionic lattices Final Conclusion: The molecular compounds are: \[ \boxed{ B \ \&\ C\ \text{Only} } \] Hence, the correct answer is: \[ \boxed{(2)} \]