Atoms of the same element that have different masses are called

ISOTOPES

Explanation:

As we know that the atoms of same element with different number of protons is known as ISOTOPES

So here we can say that

here in above example the two atoms are same with same atomic number z

but the mass number is different in it

As we know that

mass number = number of proton + number of neutrons

So isotopes must have different number of neutrons present in the nuclei

grav forces affect all objects magnetic forces affect magnetic objects and electric currents

c) up

hope this