An atom has 8 protons, 9 Neutrons, and 10 electrons. What is the mass number?

17

Explanation:

Mass number = # of protons + # of neutrons

Mass number is calculated using ONLY protons and neutrons. Electrons are not in the count.

Thus, we simply add them together: 8 + 9 = 17

This element is Oxygen - 17.

we need the questions , i may then you.

when the volume of gas is   changed from   717.73 ml   to 852 ml   the temperature will   change   from 315   c to 452   c

    calculation

this is calculated using the charles law formula

that is,   v1/t1 = v2/t2

          v1=?

        t1 = 315 c   into   kelvin = 315 +273 = 588 k

        v2 = 852   ml

        t2 = 425c + 273 =698 k

make v1   the subject of the formula ( by   multiplying both side by t1)

  v1=( v2 xt1) / t2

v1= (852 ml   x 588 k)/ 698 k= 717.73 ml