Glycerol on heating with solid KHSO4 forms When heated with potassium hydrogen sulphate, glycerol undergoes dehydration yielding an unsaturated aldehyde acraldehyde or acrolein. So the correct option is (b).

Reaction:
Glycerol, also known as glycerin, reacts with potassium bisulfate (KHSO4) upon heating to yield acrolein. The reaction can be represented as follows:

Glycerol + Potassium bisulfate → Acrolein + Potassium hydrogen sulfate

Explanation:
Glycerol is a trihydroxy alcohol with the molecular formula C3H8O3. When heated with potassium bisulfate, it undergoes a dehydration reaction, resulting in the removal of water (H2O) molecule from the glycerol molecule. This leads to the formation of acrolein, which is an unsaturated aldehyde.

Steps of the reaction:
1. Dehydration: Upon heating, glycerol loses a water molecule from one of its hydroxyl (-OH) groups, forming an alkene intermediate. This step is a dehydration reaction.

2. Rearrangement: The alkene intermediate undergoes a rearrangement to form the desired product, acrolein. In this process, the double bond in the alkene shifts to a different position in the molecule.

3. Formation of byproduct: Along with the formation of acrolein, potassium hydrogen sulfate (KHSO4) is also produced as a byproduct of the reaction.

Importance of acrolein:
Acrolein is an important intermediate in organic synthesis and is used in the production of various chemicals. It is commonly used in the manufacture of plastics, dyes, and pharmaceuticals. Acrolein is also used as a herbicide and as a fixative in perfumes.

Conclusion:
On heating glycerol with potassium bisulfate, the main product formed is acrolein. This reaction involves the dehydration of glycerol, resulting in the formation of the unsaturated aldehyde. Acrolein has significant industrial applications and is an important compound in organic synthesis.