Detailed Explanation:

Answer: Option 3 — Only three

Hydrofluorocarbons (HFCs) are synthetic compounds primarily used as replacements for ozone-depleting substances. Among the given applications, HFCs are used in aerosols (as propellants), foam agents (for blowing plastic foams), and fire retardants (as clean fire suppressants), but NOT in lubricants.

✅ Aerosols – Correct: HFCs serve as non-flammable propellants in aerosol products like hairsprays, deodorants, and cleaning sprays.
✅ Foam agents – Correct: HFCs are widely used as foam-blowing agents in manufacturing polyurethane and polystyrene foams for thermal insulation.
✅ Fire retardants – Correct: HFCs (such as HFC-227ea) are used as "clean agents" in fire suppression systems, replacing ozone-depleting Halons.
❌ Lubricants – Incorrect: Lubricants are formulated from mineral oils, synthetic hydrocarbons (polyalphaolefins), or esters, not HFCs.

📝 Short Notes: Hydrofluorocarbons (HFCs)

• Nature: Synthetic organic compounds containing hydrogen, fluorine, and carbon atoms; do not contain chlorine.
• Ozone Impact: HFCs do not deplete the ozone layer (unlike CFCs and HCFCs) as they lack chlorine and bromine.
• Climate Impact: Potent greenhouse gases with high Global Warming Potential (GWP), ranging from hundreds to thousands of times that of CO₂.
• Common Uses: Refrigeration and air conditioning, aerosol propellants, foam-blowing agents, fire suppression systems, and solvent applications.
• Regulatory Framework: Controlled under the Kigali Amendment (2016) to the Montreal Protocol, which mandates phased reduction of HFC production and consumption.
• India's Commitment: India ratified the Kigali Amendment in 2021, committing to reduce HFC use by 85% by 2047.
• Alternatives: Natural refrigerants (ammonia, CO₂, hydrocarbons), HFOs (hydrofluoroolefins) with lower GWP.