When a solid body is partially or completely immersed in a fluid, the fluid exerts an upward force on the body. The magnitude of the force is equal to
1.the mass of the body
2.the weight of the displaced fluid by the body
Which of the above is/are correct?

If the length of a copper wire is increased by twice, then its resistivity will be

Which one of the following is dimensionless quantity?

A system that does NOT allow exchange of heat with its surrounding is called