Which equation represents a physical change?
(1) h2o(s) + 6.01 kj ==> h2o(l)
(2) 2h2(g) + o2(g) ==> 2h2o(g) + 483.6 kj
(3) h2(g) + i2(g) + 53.0 kj ==> 2hi(g)
(4) n2(g) + 2o2(g) + 66.4 kj ==> 2no2(g)

Agas is contained in a thick walled balloon when the pressure changes from 1.21 atm to 2.52 the volume changes from 3.75 l to 1.72 l and the temperature change from 293k to blank k

Margaret wants to make an orange flavored drink by stirring powdered drink mix into a glass of water. she doesn't like drinks that have small clumps of powdered solid in them, so she wants the drink to be a perfect solution. what factors should margaret not consider when deciding how much powder to add to her glass of water?

6what is the importance of water on earth? a) it keeps the top layer of the geosphere cool b) it allows life to exist c) it provides ice at the poles d) it creates earth's blue color from space