Solution:

(i) Injective function: It is, also known as one-one
function and is a type of function where every element in set A has an
image in set B.
Hence, f: A → B is one-one or injection function only if $f(a) = f(b)$
has a unique solution $a = b$.
For example: $f(x) = 2x + 1$ is injection for $f: R \rightarrow R$
f(x) = f(y)
⇒ $2x + 1 = 2y + 1$
⇒ $x = y$

(ii) Surjective function: It is, also known as onto
function and is a function where for every element of set A, there is
atleast one image in set B, such that no element in Set B is left
without a match or ordered pair.
For example: $f(x) = x^2$ from the set of integers Z to the set of whole no. W is a surjective or onto function.