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.

A catalyst is a substance that alters the reaction and doesn't involve in the reaction.So if the Manganese was a catalyst the mass would not have decreased,it would just continue aletring the reaction until its used up.
The Manganese is not acting as a catalyst

Answer: it will take   4.36 seconds to reach her average velocity 10.69 miles/hour.explanation:   we have equation of motion ,where s is the displacement, a is the acceleration, u is the initial velocity and t is the time taken.average velocity = displacement/ time taken.average velocity = 10.69 miles/hr = 10.69*1.6*1000/(60*60) = 4.75 m/s4.75 = s/ts = 4. 1we also have acceleration = 2.18 m/s², initial velocity = 0 m/sso it will take   4.36 seconds to reach her average velocity 10.69 miles/hour.