The answer is on the paper
Answer:
C
Explanation:
For electromagnetic waves frequency X wavelength = speed of light
f * 2.2 x 10^-11 = 3 x 10^8 m/s
f = 3 x 10^8 / 2.2 x 10^-11
= 1.36 x 10 ^19
= 1.4 x 10^19 with two significant digits
Answer:
Option b.) Potassium ion, is written correctly.
Explanation:
Hope this helps! :)