RAC
Which class of refrigerants has the highest Ozone Depletion Potential (ODP)?
- HFCs
- HCFCs
- CFCs
- Natural Refrigerants
Explanation:
- HFCs have zero ODP but high GWP.
- HCFCs have a medium ODP (e.g., R-22 ODP=0.055).
- CFCs have the highest ODP (e.g., R-11 ODP=1.0, R-12 ODP=0.82).
- Natural refrigerants like CO2 or Ammonia have zero ODP.
What is the chemical formula for the commonly used CFC refrigerant R-12?
- CHClF₂
- CCl₄
- CCl₂F₂
- C₂H₂F₄
Explanation:
- CHClF₂ is the formula for HCFC-22 (R-22).
- CCl₄ is carbon tetrachloride.
- CCl₂F₂ is the correct formula for Dichlorodifluoromethane (R-12).
- C₂H₂F₄ is not a standard refrigerant formula.
Which protocol is the landmark international treaty designed to protect the ozone layer?
- Kyoto Protocol
- Paris Agreement
- Montreal Protocol
- Geneva Convention
Explanation:
- The Kyoto Protocol deals with greenhouse gas emissions.
- The Paris Agreement focuses on climate change mitigation.
- The Montreal Protocol on Substances that Deplete the Ozone Layer was agreed upon in 1987.
- The Geneva Convention relates to the treatment of war victims.
HFC refrigerants are considered harmful because they have:
- High Ozone Depletion Potential
- High toxicity and flammability
- High Global Warming Potential
- All of the above
Explanation:
- HFCs have zero ODP.
- Most common HFCs like R-134a are non-toxic and non-flammable (A1 safety class).
- HFCs have high Global Warming Potential (e.g., R-134a GWP = 1430). This is their primary environmental concern.
- Only High GWP is correct.
According to India’s HCFC phase-out schedule, the complete phase-out of HCFC-22 (R-22) is targeted by which year?
- 2020
- 2025
- 2030
- 2040
Explanation:
- 2020 was the year for a freeze and 67.5% reduction.
- 2025 is the year for a 90% reduction.
- 2030 is the target for a complete phase-out of HCFCs in India, as per the Montreal Protocol.
- 2040 is not a milestone year for India’s HCFC phase-out.
Which of the following is a common HFC refrigerant used as a replacement for R-12 in automotive air conditioning?
- R-22
- R-134a
- R-410A
- R-502
Explanation:
- R-22 is an HCFC used in stationary AC systems.
- R-134a (HFC-134a) became the standard replacement for CFC-12 (R-12) in automotive AC.
- R-410A is an HFC blend used as an R-22 replacement in new residential AC units.
- R-502 was a CFC/HCFC blend used in commercial refrigeration.
The “Ozone Rules” in India are officially known as:
- The Environment Protection Act, 1986
- The Ozone Depleting Substances (Regulation and Control) Rules, 2000
- The Montreal Protocol Implementation Act
- The Air Prevention and Control of Pollution Act
Explanation:
- A broader act for environmental protection.
- This is the correct official name for the “Ozone Rules” notified under the Environment Protection Act.
- This is not the name of the Indian legislation.
- This act deals with air pollution in general.
Which property of a refrigerant is indicated by its ASHRAE safety classification ‘A2L’?
- Lower toxicity and higher flammability
- Higher toxicity and lower flammability
- Lower toxicity and lower flammability
- Lower toxicity and mild flammability
Explanation:
- Describes Class B2 or B2L refrigerants.
- Describes Class B1 refrigerants.
- Describes Class A1 refrigerants (e.g., R-134a, R-410A).
- ‘A’ means lower toxicity. ‘2L’ means the refrigerant is mildly flammable with a burning velocity less than 10 cm/s. (e.g., R-32).
What is the chemical name for the HCFC refrigerant R-22?
- Dichlorodifluoromethane
- Chlorodifluoromethane
- Chlorofluoromethane
- Trifluoromethane
Explanation:
- This is the name for R-12, a CFC.
- This is the correct name for R-22 (HCFC-22).
- Not a standard refrigerant.
- This is the name for R-23, an HFC.
The Kigali Amendment to the Montreal Protocol deals with the phase-down of:
- CFCs
- HCFCs
- HFCs
- All Halocarbons
Explanation:
- CFCs were already addressed by the original protocol.
- HCFCs are being phased out under earlier amendments.
- The Kigali Amendment (2016) aims to phase down the production and consumption of HFCs due to their high GWP.
- It specifically targets HFCs.
Which of these is a natural refrigerant with zero ODP and negligible GWP?
- R-407C
- R-600a
- R-404A
- R-508B
Explanation:
- R-407C is an HFC blend with high GWP.
- R-600a (Isobutane) is a hydrocarbon, a natural refrigerant with ODP=0 and GWP≈3.
- R-404A is an HFC blend with very high GWP (≈3922).
- R-508B is an HFC/HCFC blend.
The number in a refrigerant designation (e.g., R-134) is derived from:
- Its boiling point in °C
- Its molecular weight
- A code indicating its chemical composition
- Its year of discovery
Explanation:
- It is not directly related to the boiling point.
- It is not the molecular weight.
- The numbering system is based on a rule: For methane/ethane series, the number indicates the number of Carbon, Hydrogen, and Fluorine atoms.
- It is not related to the year.
Which organization is responsible for assigning standard safety classifications (like A1, B2L) to refrigerants?
- ISO
- ASHRAE
- UNEP
- EPA
Explanation:
- ISO adopts standards but is not the primary source.
- ASHRAE Standard 34 designates the safety classification of refrigerants.
- UNEP oversees the Montreal Protocol.
- EPA sets regulations in the USA.
What does the ‘a’ suffix in R-134a signify?
- It is an azeotropic mixture
- It is an isomer with different atomic arrangement
- It is an atmospheric refrigerant
- It is an additive mixture
Explanation:
- Azeotropic mixtures have a suffix like R-500.
- The suffix (a, b, c) indicates different isomers. R-134 and R-134a have the same formula (C₂H₂F₄) but different atomic structures and properties.
- This is not a standard meaning.
- This is not a standard meaning.
Which of these is NOT a property considered when selecting a refrigerant?
- Latent heat of vaporization
- Coefficient of Performance (COP)
- Color of the refrigerant
- Operating pressures
Explanation:
- High latent heat is desirable for higher capacity.
- COP is a key performance indicator.
- The color of a refrigerant is not a functional property. Refrigerants are typically colorless.
- Operating pressures dictate system design and strength requirements.
The primary function of a refrigerant in a vapor compression cycle is to:
- Absorb heat during evaporation and reject heat during condensation
- Lubricate the compressor
- Clean the system components
- Increase the pressure of the system
Explanation:
- This is the fundamental principle of the refrigeration cycle.
- This is the function of the lubricating oil.
- Refrigerants do not clean the system.
- The compressor increases the pressure; the refrigerant is the working fluid.
Which CFC was most commonly used in domestic refrigerators before the phase-out?
- R-11
- R-12
- R-113
- R-502
Explanation:
- R-11 was used as a blowing agent for insulation foam and in large chillers.
- R-12 was the most common refrigerant for domestic refrigerators and automotive AC.
- R-113 was used as a solvent.
- R-502 was used in commercial low-temperature refrigeration.
The Montreal Protocol is often cited as a successful example of:
- International trade agreement
- Global environmental cooperation
- Military alliance
- Economic sanctions
Explanation:
- Its primary goal is not trade.
- It is universally ratified and has successfully slowed ozone depletion through global cooperation.
- It is not a military agreement.
- It uses phase-out schedules, not sanctions.
Which of these is a zeotropic refrigerant blend?
- R-502
- R-407C
- R-500
- R-12
Explanation:
- R-502 is an azeotropic blend.
- R-407C is a zeotropic blend of HFCs (R-32, R-125, R-134a) with a temperature glide.
- R-500 is an azeotropic blend.
- R-12 is a single-component refrigerant.
The “Ozone Depletion Potential” (ODP) of a refrigerant is measured relative to:
- Carbon Dioxide (CO₂)
- Ammonia (R-717)
- Trichlorofluoromethane (R-11)
- Water
Explanation:
- CO₂ is the reference for GWP (GWP=1).
- Ammonia has an ODP of 0.
- R-11 is assigned a baseline ODP of 1.0. All other ODP values are relative to it.
- Water is not a reference for ODP.
What major environmental issue are HFC refrigerants primarily associated with?
- Acid Rain
- Ozone Layer Depletion
- Climate Change / Global Warming
- Smog Formation
Explanation:
- Caused mainly by SO₂ and NOx emissions.
- HFCs have zero ODP and do not deplete the ozone layer.
- HFCs are potent greenhouse gases with high Global Warming Potential (GWP), contributing to climate change.
- Caused by ground-level ozone and particulates, not directly by HFCs.
Which hydrocarbon refrigerant is commonly used in modern domestic refrigerators?
- R-290 (Propane)
- R-600a (Isobutane)
- R-1270 (Propylene)
- R-50 (Methane)
Explanation:
- R-290 is used in commercial systems and heat pumps.
- R-600a (Isobutane) is the most common hydrocarbon refrigerant used in domestic refrigerators today.
- R-1270 is used in industrial applications.
- R-50 is not practical for domestic refrigeration.
The phase-out of CFCs in developed countries was mostly completed by:
- 1990
- 1996
- 2000
- 2010
Explanation:
- 1990 was a target for a freeze.
- Developed countries phased out major CFCs like R-11 and R-12 by 1996 under the Montreal Protocol.
- 2000 was a milestone for some HCFCs.
- 2010 was a milestone for HCFCs in developed countries.
Which of these is a primary requirement for a “drop-in” refrigerant replacement?
- It must be the same color as the original
- It must require no changes to the existing system
- It must be cheaper than the original
- It must be natural
Explanation:
- Color is irrelevant.
- A “drop-in” replacement is intended to work in an existing system with minimal changes, though some (like oil change) are often needed.
- Cost is a factor but not the defining requirement.
- Many drop-in replacements are synthetic blends.
The Ozone Depleting Substances (Regulation and Control) Rules, 2000 in India are administered by the:
- Ministry of Power
- Ministry of Road Transport and Highways
- Ministry of Environment, Forest and Climate Change (MoEF&CC)
- Ministry of Chemicals and Fertilizers
Explanation:
- Not responsible for environmental regulations.
- Not responsible for environmental regulations.
- The MoEF&CC is the nodal ministry for implementing the Montreal Protocol and related rules like the ODS Rules, 2000.
- Not the nodal ministry for ODS rules.