Need !
a scientist measures the rate of a reaction between two liquids. then he performs the reaction again, adding solid manganese. the reaction takes place more quickly the second time. the mass of the manganese decreased by 0.45 grams during the reaction. he claims that the manganese acted as a catalyst because it sped up the reaction. explain what is wrong with the scientists' reasoning.

What are the necessary conditions for fusion?

The diagram shows a boulder rolling down a hill into a valley and then up the opposite hill. at which position does the boulder have the greatest kinetic energy? a b c d

Cyclotrons are widely used in nuclear medicine for producing short-lived radioactive isotopes. these cyclotrons typically accelerate h- (the hydride ion, which has one proton and two electrons) to an energy of 5 mev to 20 mev. this ion has a mass very close to that of a proton because the electron mass is negligible—about 1 2000 of the proton’s mass. a typical magnetic field in such cyclotrons is 1.9 t. (a) what is the speed of a 5.0-mev h-? (b) if the h- has energy 5.0 mev and b = 1.9 t, what is the radius of this ion’s circular orbit?