A resistance of  10ohm is bent in the form of a closed cirle. What is the effective resistance between the two pints of any diameter of this circle?

Verrrry interesting question, your Highness.If you measure between the ends of any diameter, then half of the circle is on one side of those points, and half of it is on the other side of them.  You are measuring the effective resistance of 2 halves of the resistance, in parallel.  So the effective resistance is 1/4 of the conductor's total resistance . . . 2.5 ohms.

so circumference is 10 cm .2 divisions<pints> is the radius .thats it :)