<span>12.4 g
First, calculate the molar masses by looking up the atomic weights of all involved elements.
Atomic weight manganese = 54.938044
Atomic weight oxygen = 15.999
Atomic weight aluminium = 26.981539
Molar mass MnO2 = 54.938044 + 2 * 15.999 = 86.936044 g/mol
Now determine the number of moles of MnO2 we have
30.0 g / 86.936044 g/mol = 0.345081265 mol
Looking at the balanced equation
3MnO2+4Al→3Mn+2Al2O3
it's obvious that for every 3 moles of MnO2, it takes 4 moles of Al. So
0.345081265 mol / 3 * 4 = 0.460108353 mol
So we need 0.460108353 moles of Al to perform the reaction. Now multiply by the atomic weight of aluminum.
0.460108353 mol * 26.981539 g/mol = 12.41443146 g
Finally, round to 3 significant figures, giving 12.4 g</span>
The alkali metals are first column, alkali earth 2nd, halogens 2nd to last, and noble gases last. Hope it helps!
Is there choices? Cuz if there is i Need them
Answer: The complete reaction is as follows.
Explanation:
When nucleus of two or more atoms are bombarded together then it leads to the formation of new particles with new identity. This type of reaction are called nuclear reaction.
For example, 
Here, nitrogen atom when bombarded with a neutron then it is forming hydrogen and a carbon atom.
As total atomic mass on reactant side is (14 + 1) = 15
So, the atomic mass of carbon formed on product side is (15 - 1) = 14.
The number of protons holded by this carbon atom is (7 - 1) = 6.
Therefore, we can conclude that the complete reaction is as follows.
