Three hydrocarbons X, Y and Z are shown below:

Identify the incorrect statements about the hydrocarbons.

1. X and Y both differ by CH₂ unit.
2. X and Z both have the same degree of saturation as well as boiling point.
3. All have different general formulae
4. X show addition reaction whereas Y and Z show substitution reaction.

 

Complete Solution

Given Statements:

X and Y both differ by a CH₂ unit.

If X and Y are homologs, they would differ by a CH₂ group. This is typically true for alkanes in a homologous series.

X and Z both have the same degree of saturation as well as boiling point.

The degree of saturation refers to the number of hydrogen atoms compared to carbon atoms in a molecule. If X and Z have the same degree of saturation, they should be either both saturated or both unsaturated. However, having the same boiling point depends on intermolecular forces, which can differ due to structural differences, so this statement might be incorrect.

All have different general formulae.

If X, Y, and Z are different classes of hydrocarbons (such as alkane, alkene, and alkyne), they would indeed have different general formulas. For instance, alkanes have the formula CₙH₂ₙ₊₂, alkenes CₙH₂ₙ, and alkynes CₙH₂ₙ₋₂.

X shows an addition reaction, whereas Y and Z show substitution reactions.

Addition reactions are typical for unsaturated hydrocarbons (alkenes and alkynes), while substitution reactions are characteristic of saturated hydrocarbons (alkanes).

Final Answer 

The incorrect statements about these three hydrocarbons are I, II and IV.