Question

Which compound contain both ionic and covalent bonds?
• \( \mathrm{CH_3CH_2CHO} \)
• \( \mathrm{CH_3CH_2NH_2} \)
• \( \mathrm{CoCl_2} \)
• \( \mathrm{K_2CuCl_4} \)

• A. \( \mathrm{CH_3CH_2CHO} \)
• B. \( \mathrm{CH_3CH_2NH_2} \)
• C. \( \mathrm{CoCl_2} \)
• D. \( \mathrm{K_2CuCl_4} \)

Hint:

Complex salts often contain:
• Ionic bonds between ions
• Coordinate/covalent bonds inside complex ions Example: \[ \mathrm{K_2CuCl_4} \]

Answer 1

The Correct Option is D

Concept: Some compounds contain:
• Ionic bonds between ions
• Covalent bonds within polyatomic ions or complex ions Such compounds simultaneously exhibit both ionic and covalent character. Generally:
• Organic compounds mainly contain covalent bonds.
• Salts may contain ionic bonds.
• Complex salts may contain both ionic and coordinate/covalent bonds.

Step 1: Analyze Option (1): \( \mathrm{CH_3CH_2CHO} \) This is propanal. It contains:
• C--C bonds
• C--H bonds
• C=O bond All these are covalent bonds formed through sharing of electrons. No ionic bond is present. Hence, Option (1) is incorrect.

Step 2: Analyze Option (2): \( \mathrm{CH_3CH_2NH_2} \) This is ethylamine. All atoms involved are non-metals: \[ \mathrm{C,\ H,\ N} \] Therefore, bonding occurs through electron sharing. Thus, the compound contains only covalent bonds. Hence, Option (2) is incorrect.

Step 3: Analyze Option (3): \( \mathrm{CoCl_2} \) Cobalt chloride is predominantly ionic in nature. It mainly contains ionic attraction between: \[ \mathrm{Co^{2+}} \text{ and } \mathrm{Cl^-} \] No separate polyatomic covalent unit exists here. Hence, this option does not clearly contain both ionic and covalent bonds. Therefore, Option (3) is incorrect.

Step 4: Analyze Option (4): \( \mathrm{K_2CuCl_4} \) This compound can be represented as: \[ 2\mathrm{K^+} + [\mathrm{CuCl_4}]^{2-} \] Now observe carefully:
• Ionic bond exists between \( \mathrm{K^+} \) ions and \( [\mathrm{CuCl_4}]^{2-} \) ion.
• Inside the complex ion \( [\mathrm{CuCl_4}]^{2-} \), copper and chloride are connected through coordinate/covalent bonding. Therefore, the compound contains:
• Ionic bonding
• Covalent/coordinate bonding Hence, Option (4) is correct. Final Conclusion: The compound containing both ionic and covalent bonds is: \[ \boxed{\mathrm{K_2CuCl_4}} \] Hence, the correct answer is: \[ \boxed{(4)} \]