Answer:
a) the atomic number is 15
b) the mass number is 15+16 = 31
c) element is phosphorus
d)Group 15 period 3
One mole of oxygen gas, which has the formula O2, has a mass of 32 g and contains 6.02 X 1023 molecules of oxygen but 12.04 X 1023 (2 X 6.02 X 1023) atoms, because each molecule of oxygen contains two oxygen atoms.
The answers would be
1.b
2.c
3.a
