Which of the following is NOT a true statement?

Correct option is C

Concept Used:

Properties of a Rhombus:

Diagonals bisect each other at right angles.

Opposite angles are equal.

Sum of adjacent angles is always $$180^\circ$$​ (supplementary).

All sides are equal.

Properties of a Square:

A square is a special type of rhombus where all angles are $$90^\circ$$​​

Solution:

Option A:
True. The diagonals of a rhombus always bisect each other at right angles.

Option B:
True. All squares are rhombuses because a square satisfies all the properties of a rhombus.

Option C:
False. The sum of any pair of adjacent angles in a rhombus is always $$180^\circ$$​, as they are supplementary.

Option D:
True. All sides of a rhombus are equal in length.

Thus, Sum of any pair of adjacent angles of a rhombus is not $$\bf 180^\circ$$​.