Fill the empty parts in the following statements.

a$.$ In order to build a mod$-19$ counter the minimum number of required flip$-$fops is

b$.$ The main difference between JK and RS flip$-$flop is that

c$.$ Are the following statements true or false?

Full$-$adder always adds the carry $=1$ on top of the added two bits.

By adding a Select bit to it$,$ the same added circuit can be used in both $m$ as add or subtract.