Question

What is the SI unit of mass? How is it defined?

Answer 1

Si unit of mass is kg.. Mass is the quantity of matter contained in the body. 

Answer 2

SI unit of mass is Kg. The kilogram is a unit of mass equal to 1000 grams  

Kg is defined as the mass equal to the mass of platinum-iridium (Pt-Ir) cylinder which is stored in an air-tight jar at international bureau of weight and measures in France.

It is international prototype of the kilogram.