Which of the elements in Figure 3 has the highest ionization energy?
A. Na
B. Mg
C. K
D. Ca
I already answered this question but I got this wrong. I chose C.

B. Mg

Explanation:

Ionization energy is the energy required for the removal of valence electron from an isolated gaseous atom.

Ionization energy increases as we move across the period as the atomic size decreases as the electrons are being added to the same energy level.

Ionization energy decreases as we move down the group as the atomic size increases due to the addition of shells.

As magnesium (Mg) lies to the right of Sodium (Na) and Poatssium (K) and Calcium (Ca) lies below Magnesium (Mg), Mg has the highest ionization energy.

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 !