Through which of the following reactions number of carbon atoms can be increased in the chain?
a.  Grignard reaction               
b.  Cannizzaro’s reaction
c.  Aldol condensation         
d.  HVZ reaction

Choose the correct option:
1. (a, b)
2. (b, c)
3. (c, d)
4. (a, c)

Hint: Those reactions in which carbon-carbon bond formation takes place increases carbon atom in the chain


Grignard reaction and aldol condensation is used to increase the number of carbon atom in the chain as follows


While other two reactions Cannizzaro reaction and HVZ reaction don't lead to an increase in the number of carbon atoms.

In HVZ, the number of carbon atoms in the product remains the same as compared to the reactant. The reaction is as follows:



In Cannizzaro’s reaction, the number of carbon atoms remains the same. The reaction is as follows: