### Theory:

Mass is the quantity of matter contained in a body.

Mass is a basic property of matter. The mass of each substance is in a solid, liquid or gaseous state.

Key takeaways:

1. All the matters contain mass; that is why it is known as base quantity.

2. Mass is a scalar quantity. That is mass only has a numerical (magnitude) value.

3. The mass of an object is a constant value and, it does not vary by the changes of gravity, place, temperature or pressure.

4. In the International System of Units, the basic unit of mass is the kilogram (kg).

5. One kilogram is the mass of a particular international prototype cylinder made of platinum-iridium alloy, kept at the International Bureau of Weights and Measures at Sevres, France.
The units gram (g) and milligram (mg) are the submultiples of ten (1/10) of the unit kg. Similarly, quintal and metric tonne are multiples of ten (× 10) of the unit kg.
$\begin{array}{l}1\phantom{\rule{0.147em}{0ex}}g\phantom{\rule{0.147em}{0ex}}=\phantom{\rule{0.147em}{0ex}}\frac{1}{1000}×1\phantom{\rule{0.147em}{0ex}}\mathit{kg}\phantom{\rule{0.147em}{0ex}}=\phantom{\rule{0.147em}{0ex}}0.001\phantom{\rule{0.147em}{0ex}}\mathit{kg}\\ \\ 1\phantom{\rule{0.147em}{0ex}}\mathit{mg}\phantom{\rule{0.147em}{0ex}}=\phantom{\rule{0.147em}{0ex}}\frac{1}{1000000}\phantom{\rule{0.147em}{0ex}}×\phantom{\rule{0.147em}{0ex}}1\phantom{\rule{0.147em}{0ex}}\mathit{kg}\phantom{\rule{0.147em}{0ex}}=\phantom{\rule{0.147em}{0ex}}0.000001\phantom{\rule{0.147em}{0ex}}\mathit{kg}\\ \\ 1\phantom{\rule{0.147em}{0ex}}\mathit{quintal}\phantom{\rule{0.294em}{0ex}}=\phantom{\rule{0.147em}{0ex}}100\phantom{\rule{0.147em}{0ex}}×\phantom{\rule{0.147em}{0ex}}1\phantom{\rule{0.147em}{0ex}}\mathit{kg}\phantom{\rule{0.147em}{0ex}}=\phantom{\rule{0.147em}{0ex}}100\phantom{\rule{0.147em}{0ex}}\mathit{kg}\\ \\ 1\phantom{\rule{0.147em}{0ex}}\mathit{metric}\phantom{\rule{0.147em}{0ex}}\mathit{tonne}\phantom{\rule{0.147em}{0ex}}=\phantom{\rule{0.147em}{0ex}}1000\phantom{\rule{0.147em}{0ex}}×\phantom{\rule{0.147em}{0ex}}1\phantom{\rule{0.147em}{0ex}}\mathit{kg}\phantom{\rule{0.147em}{0ex}}=\phantom{\rule{0.147em}{0ex}}10\mathit{quintal}\end{array}$

Atomic mass unit:
Mass of a proton, neutron and electron can be determined using an atomic mass unit (amu).

In our daily life, do we use the word mass?