What is a solenoid?

A: A current-carrying sure with many coils
B: A current-carrying sure that is straight
C: A tool used to measure magnetism
D: A tool used to measure current

How many moles are equivalent to 55.5g of nano3

If you add 10ml of hot water to 10ml of cold water and the change in tempature 8°c calculate how much energy is gained by the cold water

There is one girl i like and i don't know how to tell her that, i have a feeling she knows but if she doesn't i don't want to make a fool out of myself how is one way to boost my confidence on asking her out