types of forces in nature, kinds of energy, application of this in everyday life- pressure cooker, steam engine etc

How many moles of lead are in 1.50 x 10^12 atoms of lead? could you explain the answer as well and not just give it to me i am refreshing for finals and i need to know how to do it

Achemical reaction is done in the setup shown, resulting in a change of mass. what will happen if the same reaction is done in a sealed container that is placed on the electronic balance?

How do you interpret a chromagram for what mixtures contain?