The mass spectrum represented above is most consistent with which of the following elements? Eu Gd Tb Dy

The mass spectroscopy is most consistent with the element Gd

Explanation:

Here we have the average atomic mass given by the weighted average found by multiplying the abundance in nature of the various isotopes by their observed atomic masses followed by the summation of the multiplication results as follows;

Based on approximate measurement of the chart, we have the values for the relative abundance given as follows;

Isotope, I                     Relative abundance, A                       I×A                      

154                                 1                                                         154

155                                 6                                                        930

156                                 8                                                        1248

157                                 6.2                                                     973.4

158                                 10                                                       1580

160                                 8.5                                                     1360

Sum                               39.7                                                    6245.5

Average atomic mass = 6245.5/39.7 = 157.314 atomic mass unit

Atomic mass of Eu = 151.964 u

Atomic mass of Gd = 157.25 u

Atomic mass of Tb = 158.92535 u

Atomic mass of Dy = 162.5 u

Therefore, the mass spectroscopy is most consistent with the element Gd.

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%

the answer is na (sodium)