What is the length of the longest chord in a circle of radius 5 units? Is there a smallest chord?           [Page No. 94]

The longest chord of any circle is its diameter, which passes through the centre. For a circle of radius 5 units, the diameter = $2 \times \text{radius} = 2 \times 5 = 10$ units. So the longest chord is 10 units long, a chord's length decreases as its distance from the centre increases; the diameter passes through the centre (distance 0),
so it is the longest chord.

There is no smallest chord. A chord joins two distinct points of the circle, so its length is always greater than 0. As a chord is pushed farther from the centre its length keeps shrinking towards 0, but it never reaches a least positive value whatever short chord you pick, an even shorter one can be drawn. So chords can be made as small as we like, yet none is the smallest.