A balloon contains 12.1 L of helium gas at STP. What is the mass in grams of He in the balloon?

The enthalpy of formation of water is -285.8 kj/mol. what can be inferred from this statement?

Which feature do highland climates have that lower elevation areas do not?

Three cards with holes are arranged in a straight line. a light is shined through the first card’s hole and travels through all three cards. what does this tell you about light rays? a) that light is reflected b) that light is refractive c) that light travels in a straight line d) that light does not travel in a straight line