It is 1-3-1-3
so 1Al2O3 + 3H2So4 ---> 1Al2(So4)3 + 3H2O
Charge of nucleus is always positive whether it is element or isotope.
Explanation:
Atomic number , protons and electrons have the same value / their value is same .
But for the neutron there is no specific technique. You have to remember the neutrons of every element
