Answer:
Interchangeable is something that can be used in the same manner as something else without any important differences.
or in a more simple way
something that can be exchange
For example when two sweaters look almost the same and you could easily wear either one with a particular skirt, this is an example of when the sweaters can be worn interchangeably.
Concave makes things smaller and convex makes things bigger
<span>Nuclei of u-238 atoms are </span><span>unstable and spontaneously emit alpha particles.</span>
The answer is to your question is c
Wavelength = velocity/frequency
wavelength = v/f
v= 13km/s = change this to m/s = 13000m/s
f= 14Hz
wavelength = 13000m/s÷14Hz =928.7 m