The 'laughing gas' is

ANS:A - nitrous oxide

Nitrous oxide (chemical formula: N2O) is a colorless, odorless gas with a slightly sweet taste. It is a chemical compound composed of two nitrogen atoms and one oxygen atom. Nitrous oxide is also commonly known as "laughing gas" due to its euphoric effects when inhaled in small amounts. Here are some key points about nitrous oxide:

1. Preparation: Nitrous oxide can be produced by the thermal decomposition of ammonium nitrate or by the reaction of nitric oxide (NO) with oxygen (O2).
2. Uses:
   • Anesthetic: Nitrous oxide is used in medical and dental settings as an anesthetic. When inhaled, it can produce a state of relaxation, euphoria, and analgesia (pain relief), making it useful for minor medical procedures and dental work.
   • Recreational Use: Due to its euphoric effects, nitrous oxide is sometimes abused as a recreational drug. However, inhalation of high concentrations can be dangerous and potentially lead to oxygen deprivation.
   • Industrial Applications: Nitrous oxide has various industrial applications, including as a propellant in aerosol cans, in the production of semiconductor chips, as a component in rocket propellants, and in food production as a propellant for whipped cream dispensers.
3. Environmental Impact: Nitrous oxide is a greenhouse gas and a significant contributor to global warming. It has a long atmospheric lifetime and is involved in processes that deplete the ozone layer. Despite its relatively low concentration in the atmosphere compared to other greenhouse gases like carbon dioxide, nitrous oxide has a much higher global warming potential per unit mass.
4. Safety: While nitrous oxide is generally considered safe when used appropriately in medical and dental settings, improper use or prolonged exposure to high concentrations can have adverse health effects. Inhalation of nitrous oxide in large quantities can lead to dizziness, loss of consciousness, and even death due to oxygen deprivation.