Who proposed Law of Conservation of Mass?

What are the multiples for the prefixes yocto, atto respectively?

Candela is the S.I. unit of _____

1 mole of ammonia is of 17 g. Then what is the mass of 0.3 moles of ammonia?

What’s the number of entities or particles together in mole concept known as?

1 u = Ma/NA.

A solution contains 8 moles of solute and the mass of the solution is 4 kg. What’s the molality of this solution?

What is the mass of hydrogen in terms of amu?