**Answer: Second diagram and fourth diagram.**

**Step-by-step explanation:**

A **kite** is a quadrilateral which has two pairs of congruent adjacent sides.

**In diagram 1:**

By **the distance formula**,

The sides of the given quadrilateral are , , and

Since, here a, b, c and d are unknown numbers,

Thus, this quadrilateral does not have any pair of congruent adjacent sides.

⇒ **It is not a kite.**

**In diagram 2:**

By **the distance formula**,

The sides of the given quadrilateral are , , and

Since, this quadrilateral has two pairs of congruent adjacent sides.

⇒ **It is a kite.**

**In diagram 3:**

By **the distance formula**,

The sides of the given quadrilateral are , , and

Since, here a, b, c and d are unknown numbers,

Thus, this quadrilateral only have only one pair of congruent adjacent sides.

⇒ **It is not a kite.**

**In diagram 4:**

By **the distance formula**,

The sides of the given quadrilateral are , , and

Since, this quadrilateral has two pairs of congruent adjacent sides.

⇒ **It is a kite.**