1) 
Moles of methanol = 
Mass of
that would produce 208 kg methanol =

2) Mass of sodium = 
3) Mass of mercury = 
Number of atoms of mercury = 
For one complete orbit of the earth around the sun
Sorry, Cant really tell how to differentiate the students and trial times
It is called a spring tide
This easy bro there is only one answer Gravity
but here my advance word
Sometimes the gravity of big objects would capture smaller ones in orbit. This could be one way the planet acquired the moon