how will you weight 2, 5,6,7,8??
according to me ans should be 7……1,2,4,8,16,32 and 64

Hey Friend,
For 2 Kg on one pan put 3 kg and on the other one put 1 kg
Likewise for 5 kg , 9 kg on one pan and 1+3 kg on another pan
for 6 kg,9 on one and 3 on another
for 7 kg, 1 and 9 on one and 3 on another
for 8 kg , 9 on one pan and 1 on another.
Think before you comment!!

How to weigh 15,16.. ?

For 15 kg – Put 27 kg on one and 9 kg +1 kg on other
For 16 kg – Put 27 kg on one and 9 kg   on other

Great! How did you formulate this?

I am unable to get the exact answer.Can any one tell  me the way of doing it??

it is something like
for 121= it lies between 3^1-3^4 so we consider 1,3^1,3^2,3^3,3^4.
similarly for 250 we will consider numbers from 3^1-3-5 i.e(1,3,9,27,81,243)

question says ‘to the nearest pound’, so shouldn’t  we have 0.5 pound weight too? that way if something weighs 2.25 pound we will be able to measure it as 2 pounds. otherwise it will be heavier than 2 and lighter than 3 pounds and we wont be able to tell the nearest pound.