The diameter divides a circle into two equal parts.

The length of the chord need not always be greater than the radius. Consider the figure, OP is the radius, AB is the chord.

OP = 5 cm, AB = 2 cm

Radius =  15 cm 
Diameter $=2\times \text{radius}$
= $2\times 15$
= 30 cm

In a circle of radius 6cm, the diameter will be 12 cm.
A chord is a line segment with its endpoints on the circle and we know that diameter of a circle is the largest chord of the circle.
So a chord cannot be longer than 12cm.

Given that 

The diameter of a circle = 32 cm

The radius of a circle = $\frac{Diameter}{2}$

On substituting the values we get:

The radius of the circle whose diameter is 32 cm $=\frac{32}{2}=16cm$

A chord of a circle is a line segment whose endpoints lie on the circle.

The diameter of a circle is the chord which passes through the center of the circle.

The line segment AB is a chord as it does not pass through the center of the circle.

The radius of a circle is a line segment connecting the center of the circle to any point on the circumference of the circle.

So, OA, OC, OD and OB are the radii of the given circle.

However, AB is the diameter.

The diameter of a circle is a line segment which passes through the center of the circle and whose endpoints lie on the circle.

AB and PQ are the diameters of the circle.

Given that

The length of the diameter of a circle = 96 cm

We know that, radius of a circle = $\frac{Diameter}{2}$

On substituting the values we get:

Radius of circle = $\frac{96}{2}=48cm$ 

Given that

The diameter of a circle = 20 cm

The radius of a circle = $\frac{Diameter}{2}$

On substituting the values we get:

The radius of the circle = $\frac{20}{2}=10cm$