An atom is a small unit of matter. a small atom measures about 0.1 meter. write the decimal as a power

It's simple. Count the number of digits after decimal and put the same number of zeroes after 1.

There are 10 zeroes after decimal.

So,  

In any atom of any element, you will find protons and neutrons in the nucleus of any atom 

The molar mass of a substance is defined as the mass of 1 mol of that substance, expressed in grams per mole, and is equal to the mass of 6.022 × 10 23 atoms, molecules, or formula units of that substance.