Answer is: B because it has a lower activation energy.
For all chemical reaction some energy is required and that energy is called activation energy (energy that needs to be absorbed for a chemical reaction to start), activation energy for reaction B is lower that for reaction A.
Catalysis is the increase in the rate of a chemical reaction due to the participation of an additional substance called a catalyst.
Chemical reactions occur faster with a catalyst because they require less activation energy.
Answer:

Explanation:
Hello,
In this case, for the computation of the energy loss when the cooling process is carried out, we use the shown below equation:

Whereas we need the mass, specific heat and change in temperature of iron within the process. Thus, the only value we need is the specific heat that is 0.444 J/(g°C), therefore, we compute the heat loss:

Negative sign points out the loss due to the cooling.
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Answer:
4m/s^2
Explanation:
Acc. = final velocity - initial velocity / time taken
= 50 - 10 / 10
= 40/10 = 4ms^2