Answer:
not sure
Explanation:
a physical change (can)change.,....
Natural selection requires variation between individuals. Mutations and reproduction increase genetic variation in a population. Natural selection occurs when environmental pressures favor certain traits that are passed on to offspring.
Answer:increasing the concentration of reactants
Explanation:
Collision is the phenomenon in which the reactant molecules come to nearest closness,as a result the reactants are converted into products.
Now the number of effective collision is directly proportional to the number of reactants added..
It has to be D. the time needed to boil the water decreased