Is the only known planet that is able to support living organisms.

1- mercury
2 -earth
3- mars
4- venus

What happens to energy in an open system?

Write two balanced equations 1. dissolving of solid sodium hydroxide in water 2. the reaction of sodium hydroxide solution with hydrochloric acid

Tin has ten stable isotopes. the heaviest, 124sn, makes up 5.80% of naturally occuring tin atoms. how many atoms of 124sn are present in 82.0 g of naturally occurring tin? what is the total mass of the 124sn atoms in this sample?