Answer:- 448 mL of hydrogen gas are formed.
Solution:- It asks to calculate the volume of hydrogen gas formed in milliliters at STP when 0.020 moles of magnesium reacts with excess HCl acid. The balanced equation is:

There is 1:1 mol ratio between Mg and hydrogen gas. So, the moles of hydrogen gas is also equals to the moles of Mg reacted.
moles of Hydrogen gas formed = 0.020 mol
At STP, volume of 1 mol of the gas is 22.4 L. We need to calculate the volume of 0.02 moles of hydrogen gas.

= 0.448 L
They want answer in mL. So, let's convert L to mL using the conversion formula, 1L = 1000mL

= 448 mL
So, 0.020 moles of magnesium would produce 448 mL of hydrogen gas at STP on reacting with excess of HCl acid.
The solid compound, K2SO4 contains a cation called K+ and an anion called SO42-. In this case, there are 2 atoms of potassium, 1 atom of sulfur and 4 moles of oxygen. The compound also contains ionic bonds because of the composing non-metals and metal.
If one were to match the ratio of atoms of the elements found in this molecular formula of artificial sweetener it would be :
Carbon - 7 atoms
Hydrogen - 5 atoms
Nitrogen - 1 atom
Oxygen - 3 atoms.
Larger elements are able to form in a supernova explosion because the star releases very large amounts of energy as well as neutrons, which allows elements heavier than iron to be produced.
<h3>What is Supernova?</h3>
This is referred to the explosion of a star and it resulting in larger elements being formed through a process known as nucleosynthesis and is usually accompanied by an increase in the brightness of the star.
The elements produced are usually larger than elements such as iron and examples include uranium, gold etc.
This is therefore the reason why it was chosen as the most appropriate choice.
Read more about Supernova here brainly.com/question/27492871
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The best and most correct answer among the choices provided by your question is the third choice or letter C.
Premenstrual syndrome<span> (</span>PMS<span>) has a wide variety of </span>symptoms, including mood swings, tender breasts, food cravings, fatigue, irritability and depression. It's estimated that as many as 3 of every 4 menstruating women have experienced some form of premenstrual syndrome<span>. </span>Symptoms<span> tend to recur in a predictable pattern.</span>
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