Answer:
6.67 moles
Explanation:
Given that:-
Moles of hydrogen gas produced = 10.0 moles
According the reaction shown below:-

3 moles of hydrogen gas are produced when 2 moles of aluminium undergoes reaction.
Also,
1 mole of hydrogen gas are produced when
moles of aluminium undergoes reaction.
So,
10.0 moles of hydrogen gas are produced when
moles of aluminium undergoes reaction.
<u>Moles of Al needed =
moles = 6.67 moles</u>
Answer:
a) 
b) 
c) 
d) 
Explanation:
For neutral atoms:
Atomic Number (Z)= number of protons = number of electrons
Mass number (A) = number of protons + number of neutrons
For ions with positive net charge:
Number of protons = Z + net charge
For ions with negative net charge:
Number of protons= Z - net charge
a) A = 71, Charge = +3
Number of electrons = 28
Number of protons = 28 +3 =31

b) A = 35, Z = 45+35=80, Charge = -1
Number of protons =35
Number of neutrons = 45
Number of electrons = 36
Charge = Number of protons- Number of electrons =35-36 = -1

c) Charge = +4
Number of electrons = 86
Number of protons = Z = 86+4 = 90
mass number = A = 90+142 = 232

d) Charge = +2
Atomic number = Number of protons = Z = 38
mass number = A = 87

Answer:
The correct answer is - directly; Avogadro’s.
Explanation:
At the same temperature and pressure, gases of the same or equal volume have the same number of molecules. The relation between the moles of the gases and the volume of the gases are indirectly proportional to one another at the same temperature and pressure. This law is called Avogadro's law. In the case of an ideal gas of a particular mass has the volume and moles are directly proportional.
Thus, the correct answer is - directly; Avogadro’s.