Atoms of O-16, O-17, O-18 have the same number of neutrons?

The number of neutrons are different.

Explanation: -

In 17O

The mass number is 17

The atomic number for oxygen = 8

Number of neutrons of 17O = Mass number of 17O - atomic number

= 17-8

=9

In 16O

The mass number is 16

Number of neutrons of 16O = Mass number of 16O - atomic number

= 16-8

=8

The mass number is 18

The atomic number for oxygen = 8

Number of neutrons of 18O = Mass number of 18O - atomic number

= 18-8

=10

As we can see the number of neutrons are different in each case.