Chemistry of Gases and Applications

Helium is used to fill balloons because it is much lighter than air and non-flammable, making it safe for inflating balloons. Unlike hydrogen, helium is inert and does not pose a fire risk.

Chlorofluorocarbons (CFCs) were widely used as refrigerants in refrigerators and air conditioning systems. They were phased out globally after being identified as major contributors to ozone layer depletion.

Laughing gas is the common name for nitrous oxide (N2O), so called because it induces euphoria and laughter when inhaled. It is used in medicine and dentistry as an anesthetic and analgesic.

Lachrymatory agents are chemical compounds that irritate eyes and cause tearing. Tear gas is the common name for these riot control substances, not sulfur or regular gas.

Chlorine gas was first used as a chemical weapon in World War I by Germany at the Second Battle of Ypres in April 1915. This marked the first large-scale use of poison gas in modern warfare. The other options are either incorrect chemical names or not used in WWI.

Methane gas from underwater hydrate deposits has been proposed as an explanation. The theory suggests that large methane releases could reduce water density dramatically, making ships lose buoyancy and sink rapidly. This is one of the more scientifically-grounded theories.

Nitrous oxide (N2O) is commonly called laughing gas because it produces euphoria and giggling when inhaled. It has been used as an anesthetic in dentistry and medicine since the 19th century. The other options are different nitrogen oxides or carbon compounds - nitrogen dioxide (NO2) is a brown toxic gas, nitrogen monoxide (NO) is nitric oxide, and carbon monoxide (CO) is a poisonous gas.

CFL bulbs consume significantly less energy than incandescent bulbs, leading to lower CO2 emissions from power plants. Over a CFL bulb's typical lifetime of 8-10 years, this energy savings translates to approximately 0.5 tons of CO2 emissions avoided compared to traditional incandescent bulbs.

Nitrous oxide (N2O) is commonly known as laughing gas due to its euphoric effects when inhaled. It's used in medicine and dentistry for its anesthetic and analgesic properties, and was historically used for recreational purposes.

Nitrous oxide (N₂O) is commonly known as laughing gas due to its euphoric effects when inhaled. It has been used as an anesthetic and analgesic in dentistry and medicine for over 150 years. The other options are different chemical compounds - carbon dioxide (CO₂) is not laughing gas, nitrogen (N₂) is a different gas, and sulfuric oxide is not a standard chemical name for laughing gas.

TNT is one of the most well-known explosives, standing for Trinitrotoluene. It's a yellow solid used extensively in military and mining applications. Options A, C, and D have incorrect prefixes ('tetra' means four, not three; 'tera' is not a chemical prefix).

Laughing Gas is the common name for nitrous oxide (N2O), used as an anesthetic and in dental procedures for its euphoric effects. It causes uncontrollable laughter hence the nickname. The other options are nitrogen oxides with different properties and uses.

Sarin is a potent nerve agent that disrupts the nervous system by inhibiting acetylcholinesterase. Mustard Gas is a blister agent (vesicant), Anthrax is a biological agent (bacterium), and Hydrogen Cyanide is a blood agent - none are nerve agents.

Semtex is a plastic explosive containing PETN and RDX mixed with a plasticizer to make it moldable. It was developed in Czechoslovakia and is more powerful than TNT. Options A and B are incorrect combinations; C-4 is a different plastic explosive (RDX-based, not PETN+RDX).

Chlorine gas (Cl2) is greenish-yellow in color, which gives it its name from the Greek 'chloros' meaning greenish-yellow. Hydrogen is colorless, Neon is reddish-orange in discharge tubes but colorless as a gas, and Krypton is colorless.