Please help ASAP! How many molecules of C3H7Cl would be produced if 400 grams of propane (C3H8) reacted with excess chlorine gas according to the equation below:
2C₃H₈ + Cl₂ > 2 C₃H₇Cl + H₂

Sandy is building a small toy car. he wants to use a balloon to power the toy car. he fills a balloon with air and then attaches a straw to the balloon. he tapes the balloon-straw combination to the car and then releases the end of the balloon. the toy moves forward as the air from the balloon comes out the back of the straw. what can sandy do to make the toy car move faster? a) use less air in the balloon. b) blow up the balloon more. c) use a longer straw. d) use larger tires.