Which element will have the following property in the periodic table 1)Largest atomic size 2) Highest electron affinity 3) lowest ionisation enthalpy in group II 4) gaseous form at room temperature

1) Francium

2) Chlorine

3) Barium

4) Rn, Xe, Kr, Ar, Ne, He, F, Cl, O, N and H

Explanation:

1) The atomic radius increases from the top to the bottom of a given group and decreases from the left hand side of a given period to the right of the period. Therefore looking at the bottom left of the periodic table, the atom with the largest atomic radii is Francium

2) Elements with the highest electron are located at the top right corner of the periodic table, opposite to the location of the elements with the highest atomic radius, however, although Fluorine has the highest electronegativity, Chlorine has the highest electron affinity, due to the repulsion present in the 2-p sub-shell of Fluorine

3) Ionization energies increases from bottom to top of  given group, therefore, the element with the lowest ioniztion energy in group II is the element at the bottom of the group which is Ba or barium

4) The gaseous elements are located at the top and extreme right of the periodic table and includes the elements of group 8A(radon (Rn), xenon (Xe), krypton (Kr), Argon (Ar), Neon (Ne) as well as Fluorine (F), Chlorine (Cl), Oxygen (O), Nitrogen (N), Helium (He) and Hydrogen (H).

2fe + 3h2so4 -> fe2(so4)3 + 3h2

it is necessary to balance equations in order to get the proper amount of reactants as well as products in order not to make a miscalculation.

you cannot change the subscripts as that would change the substance itself. for instance, diatomic elements such as h2 only have the subscript two when a gas. another example would be so4, if you were to change the subscript, the element would no longer be sulfate.

we change the coefficients instead as that only changes the number of molecules rather than the substance itself.

hope this !