Answer:
Option a: positron emission.
Explanation:
In the transformation we have:
⁶⁷Ga → ⁶⁷Zn
The reaction is:

For Ga to become Zn, the atom nucleus has to lose a proton, so in the given options, the reaction that involves the transformation of a proton is the option a, positron emission.
In a positron emission, a proton becomes into a neutron and a positron:

Therefore, the correct answer is option a: positron emission.
I hope it helps you!
Water, <span>rusts a nail faster</span>
Not sure about any others but I believe 3 goes with B
Answer:
CaCl2
Explanation:
For every calcium there's 2 chlorine
A mixture is a substance made by combining two or more different materials in such a way that no chemical reaction occurs.
A mixture can usually be separated back into its original components. Some examples of mixtures are a tossed salad, salt water and a mixed bag of M&M's candy.