Question : The circumferences of the two circles are touching externally. The distance between their centres is 12 cm. The radius of one circle is 7 cm. Find the diameter (in cm) of the other circle.

Option 1: 12

Option 2: 10

Option 3: 8

Option 4: 5

Question : The sum of the lengths of the radius and the diameter of a circle is 84 cm. What is the difference between the lengths of the circumference and the radius of this circle? [Use $\pi=\frac{22}{7}$]

Option 1: 156 cm

Option 2: 172 cm

Option 3: 148 cm

Option 4: 128 cm

Question : Out of two concentric circles, the radius of the outer circle is 6 cm and the chord PQ of the length 10 cm is a tangent to the inner circle. Find the radius (in cm) of the inner circle.

Option 1: $4$

Option 2: $\sqrt{7}$

Option 3: $\sqrt{13}$

Option 4: $\sqrt{11}$