Sound waves are most effective when traveling through solids. Less effective when in liquids and least effective in air.
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!
Each one is a living organism.
Answer:
Water has a very high heat capacity, which makes it useful for radiators ... the temperature change that a given substance will undergo when it is either heated or cooled. ... The heat that is either absorbed or released is measured in joules. ... A 15.0 g piece of cadmium metal absorbs 134 J of heat while rising from 24.0°C to ...