Complete the following reactions:

Explanation

I. When two molecules of aldehyde containing `alpha`-H atom react, the general formula of the aldol product is as follows:

The terminal `(-CHO)` can be converted to `(-CH_(3))` by its reduction to `(OH)` group, which can be removed by dehydration followed by reduction.
The gerneral formula is:

Only those can be synthesised which have even number of C atoms in the dotted reactangle.
a.
Yes, the alkane in (a) can be synthesised by self aldol condensation as shown below.

b. Yes, the alkane in (b) can be synthesised by self aldol condensation as shown below.

c. No. Product in (c ) cannot be synthesised by self aldol condensation.

Check:

d. No. Product in (d) cannot be synthesised by self aldol condensation.

Check:
Moreover, the total number of C atoms in compound in (d)n is 7. In self aldol condensation, the product should have even number of C atoms.

II. a.
b.