Single replacement because only one letter is being switched out in the reaction
Of heating. Or when the lake is exposed to boil because of the temperature.
Answer: C2H2
Explanation: Because each of the lines represent one bond, and because there are three lines (bonds) between the carbons, it means that they are bonded by three bonds, also known as a triple bond.
Explanation:
The scientific notation:

where
and k is integer.
We have the example:

You can write the numbers in a "normal" form:

Make the sum:

And next write it in the scientific notation:

<h3>Other method:</h3>
You can add numbers in scientific notation if the power of tens in both number is the same.
Therefore you must convert the first number:

Now, you can make the sum:

Answer:
it produces amino acids and proteins. It is also needed to make chlorophyll in plants, which is used in photosynthesis to make their food.