Find out the statements which are not true.
A. Resonating structures with more covalent bonds and less charge separation are more stable.
B. In electromeric effect, an unsaturated system shows +E effect with nucleophile and –E effect with electrophile.
C. Inductive effect is responsible for high melting point, boiling point and dipole moment of polar compounds.
D. The greater the number of alkyl groups attached to the doubly bonded carbon atoms, higher is the heat of hydrogenation.
E. Stability of carbanion increases with increase in s-character of the carbon carrying negative charge.
Show Hint
Lower heat of hydrogenation indicates higher alkene stability.
Let's assess the validity of each statement to identify which ones are not true:
Statement A: "Resonating structures with more covalent bonds and less charge separation are more stable."
This statement is true because resonance structures are more stable when they have a higher number of covalent bonds and minimal charge separation. Greater charge separation usually indicates instability.
Statement B: "In electromeric effect, an unsaturated system shows +E effect with nucleophile and –E effect with electrophile."
This statement is false. The electromeric effect involves a temporary shift of electrons in an unsaturated compound when approached by a reagent. Typically, the +E (positive electromeric effect) is seen with electrophiles, and the –E (negative electromeric effect) occurs with nucleophiles.
Statement C: "Inductive effect is responsible for high melting point, boiling point and dipole moment of polar compounds."
This statement is true because the inductive effect, which involves the polarization of sigma bonds due to electronegativity differences, contributes to the dipole moment. This polarization can indeed affect physical properties like melting and boiling points due to increased molecular interactions.
Statement D: "The greater the number of alkyl groups attached to the doubly bonded carbon atoms, higher is the heat of hydrogenation."
This statement is false. In fact, the opposite is true. More substituted alkenes (with more alkyl groups) are generally more stable and thus have lower heats of hydrogenation.
Statement E: "Stability of carbanion increases with increase in s-character of the carbon carrying negative charge."
This statement is true. Carbanions are more stable when the carbon atom that carries the negative charge has higher s-character (such as in sp-hybridized carbons) because s-electrons are closer to the nucleus and thus more tightly held.
Based on the analysis, the statements that are not true are B and D. Therefore, the correct option is:
