Answer:
2,3–dimethylpentane
Explanation:
To know which option is correct, we shall determine the name of the compound.
To obtain the name of the compound, do the following:
1. Determine the longest continuous carbon chain. This gives the parent name of the compound.
2. Identify the substituent group attached to the compound.
3. Locate the position of the substituent group by giving it the lowest possible count.
4. Combine the above to obtain the name of the compound.
Now, we shall determine the name of the compound as follow:
1. The longest continuous carbon chain is 5. Thus, the parent name of the compound is pentane.
2. The substituent group attached is methyl (–CH₃)
3. There are two methyl group attached to the compound. One is located at carbon 2 and the other at carbon 3.
4. Therefore, the name of the compound is:
2,3–dimethylpentane
None of the options are correct.
A cold air mass moves into an area of warm air
<u>Answer:</u> The longest wavelength of light is 656.5 nm
<u>Explanation:</u>
For the longest wavelength, the transition should be from n to n+1, where: n = lower energy level
To calculate the wavelength of light, we use Rydberg's Equation:

Where,
= Wavelength of radiation
= Rydberg's Constant = 
= Higher energy level = 
= Lower energy level = 2 (Balmer series)
Putting the values in above equation, we get:

Converting this into nanometers, we use the conversion factor:

So, 
Hence, the longest wavelength of light is 656.5 nm
Answer : Mass
Explanation : Mass measures the amount of matter in a substance or an object.
He did experiments with combustion and gas's