Answer:
Metal
Element: Calcium
Valency: 2
Explanation:
To find the element, let's use the periodic table. (Look below)
We already went past 3 shells, just need the 2 electrons after it.
Just skip to the 4th row and count 2 to the right
We end up at Calcium.
Calcium is a metal and we're also on the alkaline earth metals column.
Calcium will need to lose 2 electrons to reach stability, so the valency is 2.
When determining the percentage by mass of a solution, the mass of the solvent is measured last.
<h3>What is the percentage by mass of a solvent?</h3>
The percentage by mass of a solvent in a solution is the ratio of the mass of the solvent and the mass of the entire solution.
Mathematically, this can be expressed as:
Percentage by mass of solvent = mass of solvent/mass of solution x 100
Thus, given a solution, a weighing balance, an evaporating dish, and a burner:
- The mass of the evaporating dish is determined first (A)
- The mass of the evaporating dish and the solution next (B)
- Next would be to heat the solution to remove the solvent.
- The mass of the evaporating dish plus the residue is then measured (C).
Thereafter, the amount of solvent can then be determined as: (A+B) - C.
More on percentage by mass can be found here: brainly.com/question/16885872
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Answer: Protons
WHY?
Changing electrons will only result in the same element having different charges and hence, changing it's chemical properties.
Changing neutrons will not change an element but it will result in an isotope forming instead. (Isotopes are elements of the same type with different neutron numbers.)
However, changing the proton number would immediately change the nucleus composition, resulting in a change in element with a negative charge as there are more electrons than protons. This results in a expansion in valance electrons's distance from the nucleus. This results in a change in chemical properties of the element.
Therefore, a change in Protons is the answer.
<em>Here is the Answer I Hope this Helps:-</em>
<em>The closer the electrons are to the nucleus, the more tightly they are bound, thus increasing the electronegativity of the atom.</em>