<u>Answer:</u> The wavelength of the photon is 486.2 nm and it lies in the visible region
<u>Explanation:</u>
To calculate the wavelength of light, we use Rydberg's Equation:
Where,
= Wavelength of radiation
= Rydberg's Constant = 
= Higher energy level = 4
= Lower energy level = 2
Putting the values in above equation, we get:
Converting this into nanometers, we use the conversion factor:
So, 
As, the range of wavelength of visible light is 400 nm - 700 nm. So, the wavelength of the given photon lies in the visible region
Hence, the wavelength of the photon is 486.2 nm and it lies in the visible region
In order to make the dissolution of the solid compound in water to occur at a faster rate, Samuel could do the following:
1. Break down the solid into tiny particles: breaking down the solid into tiny particles increases the surface area of the solid and thus increase the quantity of the substance that comes in contact with the solvent per time, this leads to a faster dissolution of the solid.
2. Stir the liquid with iron rod: Samuel can increase the dissolution rate of the substance by stirring it continuously with iron rod.
3. Increasing the temperature:Samuel could also increase the rate of dissolution of the substance by increasing the temperature of the water.
Answer:
c
Explanation:
Nh4OH + HCL ---> NH4Cl + H3O
so ph decreases as H3O increases
and OH also decreases
