A. The wavelength of light that is emitted is 122 nm.
<h3>
What is wavelength?</h3>
Wavelength is the distance between identical points (adjacent crests) in the adjacent cycles of a waveform signal propagated in space or along a wire.
<h3>Wavelength of light is emitted</h3>
When an electron falls from the n = 2 to the n = 1 energy levels in a Hydrogen atom, the wavelength of light is emitted is calculated as follows;
¹/λ = R(1/n₁² - 1/n₂²)
¹/λ = 109677(1/1 - 1/2²)
¹/λ = 109677(1 - ¹/₄)
¹/λ = 82,257.25
λ = 1/8,225.25
λ = 1.22 x 10⁻⁵ cm
λ = 1.22 x 10⁻⁷ m
λ = 122 nm
Thus, the wavelength of light that is emitted is 122 nm.
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Desalination is a process that takes away mineral components from saline water.
There are 0.15 ml of the water contains 150 mg of Pb .
Calculation ,
Formula used :
density = mass / volume ( i )
Given mass of the Pb in milligram ( mg ) = 150 mg
Given mass of the Pb in gram ( g ) = 150 ×
= 0.15 gram
Given density = 1.0 g/ml
We have to find volume of water in milliliter ( ml ) .
Putting the value of mass of the Pb , lead and density in equation ( i ) we get the volume of water in milliliter ( ml ) .
density = mass / volume
1.0 g/ml = 0.15 gram / volume
volume = 0.15 gram / 1.0 g/ml = 0.15 ml
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Answer:- The volume of copper is 280 mL.
Solution:- Density and mass of copper metal are given and it asks to calculate the volume of it.
Density is directly proportional to mass and inversely proportional to the volume. The density formula is:

where D stands for density, M stands for mass and V stands for volume.
Since, the problem asks to calculate the volume, let's rearrange the formula for volume.

The given density is 8.9 grams per mL and the mass is 2.5 kg. We need to convert the mass unit from kg to g so that the g unit could be canceled while calculating volume.
The conversion factor is, 1kg = 1000g

= 2500g
Let's plug in the values in the density formula to calculate the volume.

= 280.89 mL
If the sig figs are considered then the answer needs to be round to two sig figs and hence the volume becomes 280 mL.
The principle of radiation protection is to trigger deterministic and stochastic effect.
Explanation:
The main aim of principle of radiation is to prevent the deterministic effects of radiation and reduce the risks of stochastic effects.
There are three general principals of radiation used for dealing with ionising radiation are Justification, Dose limitation and Optimization.
The three basic radiation principles are time, distance and shielding.
The risk of exposure to radiation is measured using the conventional unit rem or SI unit (sievert).