Rydberg formula is given by:

where,
= Rydberg constant = 
= wavelength
and
are the level of transitions.
Now, for
= 2 and
= 6

= 
= 
= 
= 

= 
= 
= 
Now, for
= 2 and
= 5

= 
= 
= 

= 
= 
= 
Now, for
= 2 and
= 4

= 
= 
= 

= 
= 
= 
Now, for
= 2 and
= 3

= 
= 
= 

= 
= 
= 
When aluminum metal is made to contact with chlorine gas (Cl₂), a highly exothermic reaction proceeds. This produces aluminum chloride (AlCl₃) powder. The balanced chemical equation for this reaction is shown below:
2Al(s) + 3Cl₂(g) → 2AlCl₃(s)
Since it was stated that aluminum is in excess, this means that the amount of AlCl₃ produced will only depend on the amount of Cl₂ gas available. The molar mass of Cl₂ is 70.906 g/mol. Using stoichiometry, we have the following equation:
(21.0 g Cl₂/ 70.906 g/mol Cl₂) x 2 mol AlCl₃/ 2 mol Cl₂ = 0.1974 mol AlCl₃
Thus, we have determined that 0.1974 <span>moles of aluminum chloride can be produced from 21.0 g of chlorine gas. </span>
Ba2+ and Cu2+, and Sr2+ and Li+
Answer:
You should follow these steps:
Count each type of atom in reactants and products.
Place coefficients, as needed, in front of the symbols or formulas to increase the number of atoms or molecules of the substances.
Repeat steps 1 and 2 until the equation is balanced.
Explanation: