We can define atomic mass the total of number of protons and number of neutrons in an atom or isotope.
<span>So when an isotope of yttrium has 39 protons and 59 neutrons, its atomic mass is equal to;
number of protons + number of neutrons = 39 + 59 = 98</span>
Because the sublevels 1s only has one shape ,and it only contains 2 elections...
Answer:
D. is the Answer. ✅
Explanation:
The Moon is 1/4 the size of Earth.
A is not right because Moon isn't a dwarf planet.❌
B is not right because the Moon isn't 1/2 the size of Earth.❌
C is not right because the Moon is no where near as large as Earth.❌
