Gymnasts often practice on foam floors, which increase the collision time when a gymnast falls. what effect does this have on collisions? the change in momentum needed to stop the gymnast is increased. the change in momentum needed to stop the gymnast is decreased. the force exerted by the floor on the gymnast decreases. the force exerted by the floor on the gymnast increases.

Nuclear fusion is the source of energy for stars. besides hydrogen, which other element is most likely also common in stars?

For the reaction, 4 a(g) + 3 b(g) => 2 c(g), the following data were obtained at constant temperature. experiment initial[a],mol/l initial [b],mol/l initial rate, m/min 1 0.200 0.150 5.00 2 0.400 0.150 10.0 3 0.200 0.300 10.0 4 0.400 0.300 20.0 which of the following is the correct rate law for the reaction? 1. rate = k[a]2[b]2 2. rate = k[a][b] 3. rate = k[a]2[b] 4. rate = k[a][b]2

How many absorptions would you expect to observe in the 13c nmr spectra of the following molecules? a) 3-chloropentane b) cis-4-methyl-2-pentene