Answer: 1.
2. 3 moles of
: 2 moles of 
3. 0.33 moles of
: 0.92 moles of 
4.
is the limiting reagent and
is the excess reagent.
5. Theoretical yield of
is 29.3 g
Explanation:
To calculate the moles :

The balanced chemical equation is:
According to stoichiometry :
3 moles of
require = 2 moles of
Thus 0.33 moles of
will require=
of
Thus
is the limiting reagent as it limits the formation of product and
is the excess reagent.
As 3 moles of
give = 2 moles of
Thus 0.33 moles of
give =
of
Theoretical yield of
Thus 29.3 g of aluminium chloride is formed.
You will want to find how many grams are in a whole mole so you know which element it is. To do this, find out how much of a mole you have.
4.95 x 10^23 atoms / 6.022 x 10^23 atoms (one whole mole of any element) = .8219860511 or ~82% of 1 mole
Now we know that, find what to multiply 20 g by to get the rest of the mole.
1 mole / .8219860511 mole = 1.216565657
20 g x 1.216565657 = ~24.33 g / mol
Now that you have grams per mole, you can look at the periodic table and the molar masses to see which this number is closely aligned.
Your answer is Magnesium (Mg), which has a molar mass of 24.305 g
Answer:
3
Explanation:
Applying,
= R/R'............... Equation 1
Where n' = number of halflives that have passed, R = Original atom of the substance, R' = atom of the substance left after decay.
From the question,
Given: R = 40 atoms, R' = 5 atoms
Substitute these values into equation 1
= 40/5
= 8
= 2³
Equation the base,
n' = 3
Answer: the ability to be dissolved, especially in water.
Explanation: I think the answer you've picked is right
Hope this helps