Examine the three listed elements of group 13. boron (b), aluminum (al), gallium (ga) if boron has two energy levels, then how many energy levels do the other two elements have? aluminum and gallium both have two energy levels. aluminum has one energy level, and gallium does not have any energy levels. aluminum has four energy levels, and gallium has three energy levels. aluminum has three energy levels, and gallium has four energy levels.

B, Al and Ga belong to group 13 in the periodic table and are present one below the other.

The energy levels of the atoms depend on the value of the principal quantum number n which is reflected in their valence electron configuration as represented below:

B = 2s²2p¹

Al = 3s²3p¹

Ga = 4s²4p¹

thus for B; n = 2, Al; n = 3 and Ga; n = 4

Ans: D) Aluminum has three energy levels, and gallium has four energy levels.

d

Explanation:

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%