What is thermal energy?

the average overall volume of a system
the total number of molecules in a system
the kinetic energy of particles in a system
the measure of temperature in a system

How many moles of oxygen react with 12 moles of aluminum

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

What causes different colors to appear in the sky? the absorption of light by air molecules the reflection of light by bodies of water the greenhouse effect in earth's atmosphere the scattering and reflection of light by dust particles