Laughing gas is the common name for Nitrous Oxide, a gas known for causing mild euphoria. You might have heard of laughing gas being used at the dentist or in medical settings. But what is it, really? The chemical name of laughing gas is Nitrous Oxide (N₂O). It is a colorless, non-flammable gas with a slightly sweet smell. It gets the name "laughing gas" because inhaling it can cause laughter and a feeling of happiness.

Nitrous Oxide works by slowing down the body’s reaction time. When inhaled in small doses, it gives a relaxing and calming effect. That is why it is often used during minor surgeries or dental treatments as a mild anesthetic. It helps reduce pain and anxiety without putting the patient fully to sleep.

In addition to medical use, Nitrous Oxide is also used in the food industry, especially in whipped cream dispensers. It acts as a propellant that helps make the cream fluffy. It is also used in the racing industry to increase engine power, although that is a completely different type of application.

Let’s look at why the other options are incorrect:
- **Nitric oxide (NO)** is a different gas used in the body for signaling and blood flow regulation.
- **Nitrogen dioxide (NO₂)** is a toxic gas found in polluted air.
- **Nitrogen pentoxide (N₂O₅)** is used in some chemical reactions but is unrelated to laughing gas.

So, when someone asks what Laughing gas really is, the correct and scientific answer is Nitrous Oxide — a chemical with both serious and interesting applications.