Answer:
The atomic number of Selenium is 34. This means that Selenium possesses 34 electrons.
The atomic number of Aluminium is 13. This means that Aluminium has 13 electrons.
Hence, there is a difference of 21 between the number of electrons in an atom of selenium and the number of electrons in an atom of aluminium.
Selenium has 6 electrons in it's outer most shell whereas aluminium has 3 electrons in its outer most shell. As a result, aluminium will have a greater tendency to lose one of its outer most electrons to become stable.
Answer:

Explanation:
First write all numerators above the common denominator
4/5 - 1/2 - 1/2=
- 1/2
Subtract the numbers
- 1/2 =
-
Write all numerators above the least common denominator 10
-
=

Subtract the numbers and you got your answer :)
First, you will have to write out and balance the equation, so:
Because we’re looking at a single element reacting with an acid, we know that the reaction must be a single replacement.
Mg + HCl —-> MgCl2 + H2
We use H2, because hydrogen can only exist by itself when covalently bonded to itself, in a diatomic state.
Mg has an oxidation state of +2, while Cl has an oxidation state of -1. Therefore, you need 2 Cl to cancel the charge fully.
Now it needs to be balanced, so you get:
Mg + 2HCl —-> MgCl2 + H2
Now we have molar ratios to do our conversions
So we’ll use stoichiometry to find the theoretical yield for both reactants, and whichever one is the LEAST is the answer.
(32.5g Mg) (1mol/24.3g) (1mol MgCl2/1 mol Mg) (95.3g/1 mol MgCl2) = 127.5g
(32.5g HCl) (1mol/36.5) (1mol MgCl2/2mol HCl) (95.3g/1 mol MgCl2) = 42.4g
So, you will get 42.4 g of MgCl2