Four atoms have the numbers of protons and neutrons given below. Which two atoms are isotopes of the same element?
W: 8 protons and 8 neutrons
X: 8 protons and 10 neutrons
Y: 10 protons and 8 neutrons
Z: 9 protons and 10 neutrons
X and Y
W and X
X and Z

W and X

Explanation:

isotopes : are masses of atoms with the same number of proton and electron but different neutron .

W and X have the same number of protons and different number of neutrons.

weight of any object is given by

w = m*g

where m is mass of the object and g is the acceleration due to gravity.

for earth the value of g is 9.8 m/s^2 so

w=117.6 n m=12 g=?

117.6=12g => g=9.8 m/s^2

which is the force of gravity on earth.