19. Which two have the same mass? a. Atoms 1 and 2 b. Atoms 2 and 4 c. Atoms 1 and 4 d. Atoms 2 and 3

Atom 2 and 4

Explanation:

The following data were obtained from the question:

Atom > Proton > Neutron > Electron

1 >>>>> 8 >>>>>> 10 >>>>>> 8

2 >>>> 10 >>>>>> 9 >>>>>> 10

3 >>>>> 9 >>>>>> 9 >>>>>> 9

4 >>>>> 8 >>>>>> 11 >>>>>> 8

Next, we shall determine the mass number of each atom. This can be obtained as illustrated below:

Atom 1:

Proton = 8

Neutron = 10

Mass number =?

Mass number = Proton + Neutron

Mass number = 8 + 10

Mass number = 18

Atom 2:

Proton = 10

Neutron = 9

Mass number =?

Mass number = Proton + Neutron

Mass number = 10 + 9

Mass number = 19

Atom 3:

Proton = 9

Neutron = 9

Mass number =?

Mass number = Proton + Neutron

Mass number = 9 + 9

Mass number = 18

Atom 4:

Proton = 8

Neutron = 11

Mass number =?

Mass number = Proton + Neutron

Mass number = 8 + 11

Mass number = 19

Summary:

Atom >>>> Mass number

1 >>>>>>>> 18

2 >>>>>>>> 19

3 >>>>>>>> 18

4 >>>>>>>> 19

From the above illustration,

Atom 1 and 3 have the same mass number

Atom 2 and 4 also have the same mass number

the answer is 0.42 is that is an option. this question provides no info