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

= 
= 
= 

= 
= 
= 
Answer:
38.541 × 10¹⁹ formula units
Explanation:
Given data:
Mass of chromium sulfate = 0.25 g
Formula units in 0.25 g = ?
Solution:
The given problem will solve by using Avogadro number.
It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.
The number 6.022 × 10²³ is called Avogadro number.
For example,
18 g of water = 1 mole = 6.022 × 10²³ formula units of water
Number of moles of chromium sulfate = Mass / molar mass
Number of moles of chromium sulfate = 0.25 g/ 392.16 g/ mol
Number of moles of chromium sulfate = 6.4 × 10⁻⁴ moles
Number of formula units:
1 mole = 6.022 × 10²³ formula units
6.4 × 10⁻⁴ moles × 6.022 × 10²³ formula units / 1 mol
38.541 × 10¹⁹ formula units
Because displacement of water is the convenient way to obtain gas.
Answer:
Bi (Bismuth)
Ag (Silver)
Li (Lithium)
Explanation:
Xe (Xenon) and I (Iodine) are non-metals. They cannot from a metallic bond because metallic bonds are bonds between metals only.