It's replacement reaction. Hope it helped
Answer:
B. Cl.
Explanation:
These are Group 7 elements whose reactivity reduces as you go down the group. Chlorine has a smaller atoms than the rest and has a stronger tendency to grab an electron in its valency shell. This is because its nucleus is closer to the outer electrons than the other elements.
Answer:Calorimetry
Explanation: In this case, an instrument called Calorimeter is used to measure the amount of heat being transferred
It looks like part of the Periodic Table. Do you have to write down the most common Periodic Table elements? If so, then that's probably what you should do.