Answer:
+2
Explanation:
Elements in group 2A have 2 valence electrons in their outer shell, so when they bond with other atoms, they are most likely to give away these 2 electrons. With 2 electrons gone, the ion will have a positive charge (since there are now more protons than electrons in the atom).
Answer: The percent of yield is 50.03%.
Explanation:
First, we need to balance the equation:
⇒ 
We need to remember that the chemical equations are written in moles, so we have to convert the amounts in grams to moles, using the molecular weight of every compound: Al2O3 (101.96 g/mol), Al (29.98 g/mol) and O2 (31.99 g/mol).
In consequence, the amounts in moles of every compound will be:



Now, we have to find out which is the limit reagent or in other words, which of the reagents will be consumed first, taking into account the stoichiometric ratio of the balanced equation:


As you can see, the maximum amount (theoretically) of Al2O3 that can be produced is 0.1665 mol.
Finally, we have to use the yield formula to calculate the percent yield of the reaction:

Therefore, the percent of yield is 50.03%.
The type of substances that would make good conductors would be substances that has greater density. This would mean that the particles of the substance are much closer to each other and would allow the free flow of the electrons in the substance. With this, current would be able to flow freely.
Explanation:
first find the the number of moles of of zinc .
as the number of moles of zinc and ZnCl2 is same we can calculate the mass of ZnCl2.