Solve this and Get a Chocolate

There are 'N' baskets in a room.All the baskets are numbered from 1 to N.Each basket is full with chocolate's. The weight of the chocolate in each basket it the same as the number assigned to it.

Now, if the situation is clear we will proceed to the next level. You are informed that one of the baskets has a chocolate the weight of which is not the same as the number on the basket.

I have an electronic weighing machine with me. You can make use of this machine to find out the odd basket. However, you have to answer the following question before you get a chance to use the weighing machine.

i) What is the minimum number of times you need to use the weighing machine.

ii) Justify the answer for the above question.