I believe it has a positive
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A rocks or a desk would be molecular solid. Ex. gas is not a molecular solid.
Answer:- The wavelength is
and the right option is D.
Solution:- Wavelength is inversely proportional to the frequency and the equation is:

where,
is the wavelength, c is the speed of light and
is frequency.
Frequency is
and the speed of light is
.
Since, 
So, 
Let's plug in the values in the equation:


Hence, the right option is D)
.
A mixture can be separated by looking at the physical properties of the components of the mixture.
Since salt is soluble in water, it can be added to the mixture to dissolve the salt.
The bar magnet is now introduced in order to remove the iron filings since they are attracted by a magnet.
The solution is filtered to separate the sand from the salt solution.
Lastly, the salt solution is heated to dryness to drive away the water and obtain the solid salt.
Hence the mixture has been separated into its components using their individual physical properties. Option A is the correct answer.
Learn more: brainly.com/question/12160179