To answer this question, you need to be familiar with the common name of certain gases.
The gas known as "laughing gas" is nitrous oxide, which is represented by the chemical formula N2O.
Let's go through each option to understand why it is correct or incorrect:
Option A) NO2 - This option is incorrect. NO2 is nitrogen dioxide, not nitrous oxide.
Option B) NO2 + N2O - This option is incorrect. NO2 is nitrogen dioxide, and N2O is nitrous oxide. The correct representation for nitrous oxide is N2O, not NO2 + N2O.
Option C) N2O - This option is correct. N2O is the chemical formula for nitrous oxide, which is commonly referred to as "laughing gas."
Option D) CHNO2N4 - This option is incorrect. The chemical formula CHNO2N4 does not represent nitrous oxide.
Therefore, the correct answer is option C) N2O. This option is correct because N2O is the chemical formula for nitrous oxide, which is commonly known as "laughing gas."