Answer:
Weight is always equal to mg.
as we know the formula
Weight=mass(m)× acceleration due to gravity (g)
Your may may be when our weight is equal to Zero.
Our weight is zero:1) at the center of the earth because value of g is 0 there
2)in the space at null point
3)during weightlessness
i guess it may be your required answer.please have a look and reply