Each diagram below represents the nucleus of a different atom.

The letters D, E, and Q show nuclei from the same element.

One of the characteristics that make an element to be different from others is the number of protons. This means each element has a defined number of protons, and this cannot be changed without changing the identity of the element itself. Here are some examples:

In the image, the number of protons is identified with the letter "p". This means atoms D, E, and Q have all one proton, while atom R has two protons.

Based on this, the atoms that belong to the same element are D, E, and Q.

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c is the answer because when something is left after something evaporates that shows the chemical change.

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%