How many atoms are in 9.01 grams of
Beryllium (Be)?

the atomic number is 4

Explanation:

the atomic number is 4, thus beryllium contains 4 electrons and 4 protons.

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137             subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54               subtract 54 from both sides.

40 = z

answer