RRB ALP CBT2 RAC Refrigerants Question bank

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.