The correct answer is: wavelength =
4562 nm
Explanation:Rydberg's formula is given as:
![\frac{1}{\lambda} = R[ \frac{1}{n_1^2} - \frac{1}{n_2^2} ]](https://tex.z-dn.net/?f=%20%5Cfrac%7B1%7D%7B%5Clambda%7D%20%3D%20R%5B%20%5Cfrac%7B1%7D%7Bn_1%5E2%7D%20%20-%20%5Cfrac%7B1%7D%7Bn_2%5E2%7D%20%5D%20)
--- (1)
Where
R = Rydberg's constant = 1.096 * 10^7 per meter

= 5

= 7
λ = Wavelength
Plug in the values in (1):
(1)=>
![\frac{1}{\lambda} = (1.096 * 10^7)[ \frac{1}{5^2} - \frac{1}{7^2} ]](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7B%5Clambda%7D%20%3D%20%281.096%20%2A%2010%5E7%29%5B%20%5Cfrac%7B1%7D%7B5%5E2%7D%20-%20%5Cfrac%7B1%7D%7B7%5E2%7D%20%5D)
Clear question is;
An ice cube is placed in the sun. Later there is a puddle of water. Later still the puddle is gone. What kind of change has occurred?
Answer:
Physical change.
Explanation:
There are two type of changes called physical change and chemical change.
In Physical changes, there is only change in the appearance of the substance and not its chemical composition. Whereas, in Chemical changes the substance changes entirely into another substance with a new chemical formula.
Now, for the ice cube, it has melted from a solid state to a liquid state. Thus, there is only a change in appearance and not its chemical composition. Thus, it's a physical change that has occurred.
Answer: The electron number density (the number of electrons per unit volume) in the wire is
.
Explanation:
Given: Current = 5.0 A
Area = 
Density = 2.7
, Molar mass = 27 g
The electron density is calculated as follows.

where,
= density
M = molar mass
= Avogadro's number
Substitute the values into above formula as follows.

Thus, we can conclude that the electron number density (the number of electrons per unit volume) in the wire is
.
At Korona100 I don’t think it’s 10, becz I remember having this question on my test/ quiz but I got it incorrect so yeah.