25
what does atomic number describe?

a. mass

b. number of neutrons

c. number of protons

d. atomic weight
what is the number of protons plus the number of neutrons in the nucleus of an atom equivalent to?

a. atomic charge

b. mass number

c. atomic number
d. average atomic mass

1 is c 2 is b

Explanation:

because atomic number is the number of protons in a nucleus

2..because the number of protons plus number of neutrons is equal to mass number.

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