To find the mole of a substance, you take the mass divided by the molar mass of that substance~
Explanation:
Tollens' reagent is prepared by using two-step process : -
Step 1:
Silver oxide is formed by mixing aqueous silver nitrate with base like sodium hydroxide. The reaction is shown below as:

Step 2
Ammonia solution is drop-wise added until all the silver oxide dissolves to form the reagent. The reaction is shown below as:

Most of the substances found on earth are compounds.
(water is made up of 2 elements)
(a baseball is larger than a golf ball by default)
(water has a pH value of 7)
Hope this helps u!
It is called convection. When warm air, or current, moves up and disperse outwards as cold air, or current, moves into the warmer region.