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RTO Hazardous Goods Test study materials
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RTO Hazardous Goods Test practice questions

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Question 1Hazardous goods classification and hazard classes

Under the ADR/RID classification system, which class covers flammable liquids?

  1. Class 8
  2. Class 2
  3. Class 5
  4. Class 3 Correct answer.

Explanation

Class 3 is the hazard class for flammable liquids, defined by flash point and initial boiling point criteria. Class 2 covers gases, Class 5 oxidizers and organic peroxides, and Class 8 corrosives.

Question 2Hazardous goods classification and hazard classes

A substance has a flash point of 35 °C and an initial boiling point of 120 °C. Which packing group applies to this Class 3 liquid?

  1. Packing group III Correct answer.
  2. Packing group I
  3. No packing group is assigned
  4. Packing group II

Explanation

For flammable liquids, packing group III applies when the flash point is above 23 °C up to 60 °C and the initial boiling point exceeds 35 °C. Packing group II requires a flash point below 23 °C, and packing group I a boiling point of 35 °C or less.

Question 3Hazardous goods classification and hazard classes

Which hazard class is assigned to substances that are liable to spontaneous heating and then catch fire?

  1. Class 4.2 Correct answer.
  2. Class 6.1
  3. Class 4.3
  4. Class 4.1

Explanation

Class 4.2 covers pyrophoric substances and self-heating substances that can ignite without an external ignition source. Class 4.1 covers flammable solids and Class 4.3 substances that emit flammable gases on contact with water.

Question 4Hazardous goods classification and hazard classes

A liquid is classified in Class 8. What is the primary hazard that defines this class?

  1. It is toxic when inhaled in confined spaces
  2. It polymerizes violently when heated
  3. It supports combustion by releasing oxygen
  4. It destroys living tissue on contact and damages other cargo or the tank Correct answer.

Explanation

Class 8 is the class for corrosive substances, which cause full-thickness destruction of skin and can also corrode metals. The defining criterion is chemical attack on living tissue, not flammability or toxicity.

Question 5Hazardous goods classification and hazard classes

Which division of Class 2 covers aerosols and liquefied petroleum gas under pressure?

  1. Division 2.3
  2. Division 2.1
  3. Division 2.4
  4. Division 2.2 Correct answer.

Explanation

Division 2.2 covers non-flammable, non-toxic compressed, liquefied or dissolved gases, including aerosols and LPG where they are non-flammable. Division 2.1 covers flammable gases and Division 2.3 toxic gases.

Question 6Hazardous goods classification and hazard classes

A consignment contains a substance with the proper shipping name UN 1203 PETROL. What does the UN number identify?

  1. The specific hazardous substance or article in the UN Model Regulations Correct answer.
  2. The manufacturer of the substance
  3. The packing group of the substance
  4. The country of origin of the shipment

Explanation

A UN number is a four-digit identifier assigned to a specific hazardous substance or article in the UN Model Regulations and listed in the dangerous goods list. It is used together with the proper shipping name to uniquely identify the entry.

Question 7Hazardous goods classification and hazard classes

Which of the following is the correct proper shipping name format for a hazardous substance?

  1. Acetone, Class 3, UN 1090
  2. Class 3, UN 1090, Acetone
  3. ACETONE, UN 1090, Class 3, PG II Correct answer.
  4. UN 1090, Acetone, Class 3

Explanation

The proper shipping name is written in upper case followed by the UN number, class and packing group in a standard sequence on documents and markings. The name must match the dangerous goods list entry exactly, not a trade name.

Question 8Hazardous goods classification and hazard classes

What is the primary hazard of Class 5.2 organic peroxides?

  1. They are thermally unstable and can undergo exothermic self-accelerating decomposition Correct answer.
  2. They are non-flammable and inert
  3. They are always toxic by inhalation
  4. They are corrosive to aluminium only

Explanation

Organic peroxides are thermally unstable and can decompose exothermically, potentially leading to fire or explosion when temperature control is lost. This is why they are subject to temperature-control and quantity restrictions.

Question 9Hazardous goods classification and hazard classes

A substance is assigned to Class 6.2. Which type of hazard does this class address?

  1. Infectious substances Correct answer.
  2. Radioactive material
  3. Miscellaneous dangerous substances
  4. Toxic gases

Explanation

Class 6.2 covers infectious substances, including biological agents capable of causing disease in humans or animals. Radioactive material is Class 7 and toxic gases are Division 2.3.

Question 10Hazardous goods classification and hazard classes

Which class covers substances that, in contact with water, emit flammable gases?

  1. Class 4.3 Correct answer.
  2. Class 4.2
  3. Class 5.1
  4. Class 4.1

Explanation

Class 4.3 is specifically for substances that react with water to release flammable gases, which can then ignite. This is distinct from self-heating (4.2) and readily combustible solids (4.1).

Question 11Hazardous goods classification and hazard classes

Which of the following best describes a Class 7 radioactive substance?

  1. Any material containing uranium only
  2. Any substance with a flash point below 60 °C
  3. Any substance that glows in the dark
  4. Any material that emits ionizing radiation above natural background and is subject to transport controls Correct answer.

Explanation

Class 7 covers materials that emit ionizing radiation and are subject to transport requirements based on activity concentration and dose rate. The class is not limited to uranium and is unrelated to flammability.

Question 12Hazardous goods classification and hazard classes

A substance is a liquid with a flash point of 12 °C and an initial boiling point of 80 °C. Which packing group is assigned?

  1. Packing group III
  2. Packing group II Correct answer.
  3. Packing group I
  4. Packing group IV

Explanation

Packing group II applies to flammable liquids with a flash point below 23 °C and an initial boiling point above 35 °C. Packing group I is reserved for liquids with an initial boiling point of 35 °C or less.

Question 13Hazardous goods classification and hazard classes

Which class covers substances that may cause severe environmental damage if released, such as certain pesticides?

  1. Class 9 Correct answer.
  2. Class 8
  3. Class 5.2
  4. Class 6.1

Explanation

Class 9 covers miscellaneous dangerous substances, including environmentally hazardous substances such as some pesticides and polychlorinated biphenyls. Environmentally hazardous substances are assigned to Class 9 when they meet the aquatic toxicity criteria.

Question 14Hazardous goods classification and hazard classes

Which of the following is a criterion for classifying a substance as Class 1 explosive?

  1. It is capable of producing gas at such a temperature and pressure and at such a speed as to cause damage to the surroundings Correct answer.
  2. It has a flash point above 60 °C
  3. It is a gas stored under pressure
  4. It is corrosive to steel

Explanation

Class 1 covers substances and articles that can produce gas at high temperature and pressure rapidly enough to damage surroundings through explosion. This definition distinguishes explosives from compressed gases and flammable liquids.

Question 15Hazardous goods classification and hazard classes

Which hazard class is assigned to a substance that is toxic by inhalation and has an LC50 (inhalation) of 0.5 mg/L for dust and mist?

  1. Class 9
  2. Class 8
  3. Class 2.3
  4. Class 6.1 Correct answer.

Explanation

Acute inhalation toxicity for dusts and mists is a Class 6.1 criterion; the LC50 threshold determines the packing group. Division 2.3 applies only to gases, and Class 8 and 9 do not capture inhalation toxicity as their primary hazard.

Question 16Hazardous goods classification and hazard classes

A substance is corrosive to steel and also has a flash point of 45 °C. Which classification approach is correct?

  1. Assign both Class 3 and Class 8 and determine precedence for the primary hazard Correct answer.
  2. Assign only Class 8 because corrosivity dominates
  3. Assign Class 9 because the hazards conflict
  4. Assign only Class 3 because flammability dominates

Explanation

When a substance meets the criteria of more than one class, it must be classified for each hazard; the dangerous goods list entry then determines the primary hazard and any subsidiary risk. Precedence rules do not eliminate the secondary hazard.

Question 17Hazardous goods classification and hazard classes

Which of the following is a Class 3 flammable liquid criterion?

  1. Flash point not more than 60 °C Correct answer.
  2. Initial boiling point above 200 °C
  3. Melting point below 0 °C
  4. Flash point above 93 °C

Explanation

Class 3 liquids are those with a flash point of not more than 60 °C, subject to the closed-cup test method. Liquids with higher flash points may still be combustible but are not Class 3.

Question 18Hazardous goods classification and hazard classes

What does the term 'subsidiary risk' mean for a dangerous goods entry?

  1. A risk that exists only when the substance is wet
  2. A risk that is less important than the primary hazard but must still be communicated Correct answer.
  3. A risk that only applies during air transport
  4. A risk that is ignored if the primary hazard is Class 1

Explanation

A subsidiary risk identifies an additional hazard of a substance that is not its primary hazard, and it must be shown in documentation and on labels. It does not replace the primary hazard class.

Question 19Hazardous goods classification and hazard classes

Which class covers desensitized explosives that are solid and do not meet the criteria for Class 1?

  1. Class 4.1 Correct answer.
  2. Class 4.3
  3. Class 5.1
  4. Class 3

Explanation

Solid desensitized explosives that do not meet the Class 1 criteria are assigned to Class 4.1. This reflects their flammability risk rather than explosive behaviour.

Question 20Hazardous goods classification and hazard classes

A gas has an LC50 (inhalation) of 2,500 ppm and is not flammable. Which Class 2 division is most appropriate?

  1. Division 2.4
  2. Division 2.3
  3. Division 2.1
  4. Division 2.2 Correct answer.

Explanation

A non-flammable gas with an LC50 above the toxic threshold is assigned to Division 2.2. Division 2.3 requires an LC50 of 5,000 ppm or less, and Division 2.1 requires flammability.

Question 21Hazardous goods classification and hazard classes

Which hazard class covers substances that are oxidizing and can cause or contribute to the combustion of other material?

  1. Class 5.2
  2. Class 6.1
  3. Class 5.1 Correct answer.
  4. Class 8

Explanation

Class 5.1 covers oxidizing substances which, while not necessarily combustible, can yield oxygen and cause or contribute to the combustion of other material. Organic peroxides are Class 5.2.

Question 22Hazardous goods classification and hazard classes

Which of the following is a criterion for a substance to be classified as Class 8 corrosive?

  1. It causes full-thickness destruction of intact skin in an animal test Correct answer.
  2. It has a flash point below 23 °C
  3. It is toxic by ingestion only
  4. It emits radiation above background

Explanation

Class 8 classification is based on the ability to cause full-thickness destruction of skin, or on corrosion of metals such as steel or aluminium. Flash point and toxicity are criteria of other classes.

Question 23Hazardous goods classification and hazard classes

Which class covers substances and articles that do not meet the criteria for any other class but still present a hazard during transport?

  1. Class 9 Correct answer.
  2. Class 6.2
  3. Class 8
  4. Class 7

Explanation

Class 9 is a residual class for miscellaneous dangerous substances and articles that present a transport hazard but do not fit Classes 1 to 8. It includes environmentally hazardous substances and elevated-temperature substances.

Question 24Hazardous goods classification and hazard classes

A substance is assigned to Class 1, Division 1.4. What does this division indicate?

  1. Extreme sensitivity to heat
  2. Minor explosion hazard where the explosive effect is largely confined to the package Correct answer.
  3. Projection hazard with no significant blast
  4. Mass explosion hazard

Explanation

Division 1.4 covers articles or substances presenting only a minor explosion hazard, with effects largely confined to the package and no projection of fragments of appreciable size. Mass explosion hazard is Division 1.1.

Question 25Hazardous goods classification and hazard classes

Which of the following statements about the UN Model Regulations classification system is correct?

  1. Classification is based only on the chemical formula
  2. Classification applies only to air transport
  3. A substance can belong to only one class regardless of its properties
  4. Hazard classes are assigned based on the predominant hazard during transport Correct answer.

Explanation

The UN Model Regulations assign each substance to a class based on its predominant hazard in transport, while subsidiary risks record additional hazards. A substance may therefore carry more than one hazard label.

Question 26Hazardous goods classification and hazard classes

A substance is offered for transport as UN 1261 NITROGLYCERIN, DESENSITIZED with not less than 40% non-volatile water-insoluble phlegmatiser by mass. Under the UN Model Regulations, how is this consignment classified?

  1. Class 3, because the desensitized mixture behaves as a flammable liquid Correct answer.
  2. Class 1, Division 1.1, because nitroglycerin is inherently an explosive
  3. Class 9, because the phlegmatiser reduces the hazard to a miscellaneous level
  4. Class 4.1, because desensitized explosives are self-reactive solids

Explanation

Desensitized explosives are excluded from Class 1 when the phlegmatiser content meets the threshold in the Dangerous Goods List; UN 1261 with at least 40% non-volatile water-insoluble phlegmatiser is assigned to Class 3 as a liquid desensitized explosive. The classification follows the specific entry rather than the intrinsic properties of the pure explosive.

Question 27Hazardous goods classification and hazard classes

A consignment of gas is carried in a cylinder and the classification entry shows Division 2.3. Which hazard does this division indicate?

  1. Flammable gas
  2. Oxidizing gas
  3. Toxic gas Correct answer.
  4. Non-flammable, non-toxic gas

Explanation

Division 2.3 is the toxic gas division: substances with an LC50 for acute inhalation toxicity at or below 5,000 ppm by volume. Flammability is a separate division (2.1) and oxidising gases sit in Division 2.2 with subsidiary risk 5.1.

Question 28Hazardous goods classification and hazard classes

During classification of a liquid, test data show a flash point of 35 °C (closed cup) and an initial boiling point of 120 °C. Which packing group applies?

  1. No packing group, because the flash point is above 23 °C
  2. Packing Group II
  3. Packing Group I
  4. Packing Group III Correct answer.

Explanation

For Class 3 flammable liquids, Packing Group III covers liquids with a flash point of 23 °C or more and not more than 60 °C, with an initial boiling point above 35 °C. A flash point of 35 °C with boiling point of 120 °C falls in this band, since PG II requires a boiling point above 35 °C and a flash point below 23 °C.

Question 29Hazardous goods classification and hazard classes

A substance is being assessed for Class 8. Which measured property supports classification as corrosive to skin?

  1. A skin irritation score that fully reverses within 72 hours of exposure
  2. A vapour pressure above 300 kPa at 50 °C
  3. Destruction of intact skin tissue after an exposure of up to 4 hours Correct answer.
  4. An acute dermal LD50 of 2,000 mg/kg body weight

Explanation

Class 8 corrosivity is based on the destruction of intact skin tissue, or on irreversible damage to skin, following exposure of up to four hours. Reversible irritation within the observation period is not sufficient for Class 8, and dermal lethality belongs to Class 6.1.

Question 30Hazardous goods classification and hazard classes

Which statement correctly describes Division 6.1 of the UN Model Regulations?

  1. It covers substances toxic by ingestion, dermal contact or inhalation Correct answer.
  2. It covers genetically modified micro-organisms only
  3. It covers infectious substances affecting humans and animals
  4. It covers substances that deplete the ozone layer

Explanation

Division 6.1 is the toxic substances division: substances with an LD50 or LC50 at or below the thresholds for oral, dermal or inhalation exposure. Infectious substances are Division 6.2, and ozone-depleting substances are handled as Class 9.

Question 31Hazard communication: labels, placards, and markings

Under the ADR hazard communication system, what does the class number shown in the bottom corner of a hazard label identify?

  1. The packing group assigned to the substance
  2. The nature of the hazard posed by the substance Correct answer.
  3. The UN number of the substance
  4. The compatibility group of the substance

Explanation

The class number in the lower corner of an ADR label indicates the hazard class, that is, the type of danger the substance presents, such as flammable, toxic or corrosive. The UN number appears separately in the top corner when required, and packing group and compatibility group are not shown in that position.

Question 32Hazard communication: labels, placards, and markings

A consignment of petrol is carried in a tank vehicle. Which placard must be displayed on the vehicle?

  1. A Class 9 miscellaneous placard bearing the UN number 1202
  2. A Class 3 placard without any UN number
  3. A Class 2 flammable gas placard bearing the UN number 1203
  4. A Class 3 flammable liquid placard bearing the UN number 1203 Correct answer.

Explanation

Petrol is UN 1203, a Class 3 flammable liquid. Tank vehicles carrying dangerous goods must display placards that combine the hazard class with the UN number of the substance, so the correct placard is Class 3 with UN 1203.

Question 33Hazard communication: labels, placards, and markings

What is the correct orientation requirement for a hazard label applied to a package?

  1. The label must be placed on the top face of the package
  2. The label must be applied horizontally, reading left to right Correct answer.
  3. The label must be placed on the bottom face of the package
  4. The label must be applied at a 45-degree angle to the package edge

Explanation

Hazard labels must be affixed horizontally so that the text and symbols read normally from left to right, with the label set at a 45-degree angle only in the diamond shape itself. Placing labels on top or bottom faces does not satisfy the requirement for visibility on the sides.

Question 34Hazard communication: labels, placards, and markings

Which marking is required on every package containing dangerous goods before it is offered for transport?

  1. The date of manufacture of the substance
  2. The expiry date of the substance
  3. The consignor's telephone number
  4. The proper shipping name and the UN number Correct answer.

Explanation

Each package must bear the UN number and the proper shipping name of the dangerous goods it contains, in addition to the applicable hazard labels. These markings let responders and handlers identify the contents without opening the package.

Question 35Hazard communication: labels, placards, and markings

What does the orange-coloured plate displayed on the front and rear of a tank vehicle communicate to emergency responders?

  1. The maximum permissible gross vehicle weight
  2. The driver's qualification level and licence category
  3. The hazard identification number and the UN number of the load Correct answer.
  4. The transport route and destination of the vehicle

Explanation

The orange plate carries two numbers: the hazard identification number on top, which describes the type and severity of the danger, and the UN number below, which identifies the substance. Together they allow responders to select the correct emergency action.

Question 36Hazard communication: labels, placards, and markings

A package bears a label showing a flame symbol. Which hazard class does this label indicate?

  1. Class 4 flammable solids
  2. Class 5 oxidizing substances
  3. Class 8 corrosive substances
  4. Class 3 flammable liquids Correct answer.

Explanation

The flame symbol on a red diamond is the standard label for Class 3 flammable liquids. Other classes use different symbols, such as a flame over a circle for oxidizers or a corrosion symbol for Class 8.

Question 37Hazard communication: labels, placards, and markings

Which of the following is the correct format for a UN number marking on a package?

  1. UN-1203-A
  2. UN 1203 Correct answer.
  3. U.N. 1203
  4. 1203 UN

Explanation

The UN number is written as the letters UN followed by a space and the four-digit number, for example UN 1203. The letters must precede the number and no additional characters are inserted.

Question 38Hazard communication: labels, placards, and markings

A shipper is preparing a package of a Class 8 corrosive liquid in a non-UN-specification fibreboard box for air transport. Which statement best describes the labelling obligation?

  1. No labels are required because the box is not UN specification
  2. Labels are required only if the package exceeds 30 kg
  3. Only the corrosive label is needed because the box is not UN specification
  4. The corrosive label and the UN number marking are required regardless of the packaging type Correct answer.

Explanation

The labelling and marking requirements attach to the dangerous goods themselves, not to whether the packaging is UN specification. A package containing a Class 8 substance must carry the corrosive label and the UN number marking even if the outer packaging is not certified.

Question 39Hazard communication: labels, placards, and markings

A vehicle carries two different dangerous goods in packages. Under the segregation and placarding rules, when may the vehicle display only one set of placards?

  1. When the journey is shorter than 50 kilometres
  2. When the total quantity carried is below the placarding threshold for each substance Correct answer.
  3. When the goods are packed in UN specification packaging
  4. When the driver holds an ADR certificate

Explanation

Placarding is required only when the quantity of dangerous goods exceeds the threshold set in the regulations. Below that threshold, the vehicle need not display placards for that substance, so a mixed load below the thresholds may require none.

Question 40Hazard communication: labels, placards, and markings

What is the purpose of the marine pollutant mark on a package?

  1. To show that the package contains a radioactive source
  2. To certify that the package is safe for air transport
  3. To identify substances harmful to the aquatic environment Correct answer.
  4. To indicate that the substance is corrosive to metals

Explanation

The marine pollutant mark identifies substances that are environmentally hazardous to aquatic life when released into water. It is separate from the hazard class label and signals the need for spill prevention measures during transport.

Question 41Hazard communication: labels, placards, and markings

A consignment contains a substance with the proper shipping name 'ACETONE' and UN number 1090. Which combination should appear on the package marking?

  1. ACETONE, UN 1090 Correct answer.
  2. ACETONE, class 3
  3. 1090, flammable
  4. UN 1090, acetone solution

Explanation

The proper shipping name must be shown together with the UN number, in that order and in capital letters as listed. The correct marking is therefore ACETONE followed by UN 1090.

Question 42Hazard communication: labels, placards, and markings

Which hazard label would be applied to a substance classified as an organic peroxide that also requires temperature control?

  1. Class 5.1 oxidizing substance label
  2. Class 4.1 flammable solid label
  3. Class 5.2 organic peroxide label plus a temperature-control label Correct answer.
  4. Class 5.2 organic peroxide label only

Explanation

Organic peroxides carry the Class 5.2 label, and when the substance requires temperature control for safety, an additional temperature-control label must be applied. Both labels are needed to communicate the full hazard.

Question 43Hazard communication: labels, placards, and markings

What does a hazard identification number beginning with the digit 4 on an orange plate indicate?

  1. The substance is a flammable solid Correct answer.
  2. The substance is radioactive
  3. The substance is a corrosive
  4. The substance is an infectious substance

Explanation

In the hazard identification number system, a leading 4 indicates a flammable solid or a spontaneously reactive substance. Other leading digits identify different hazards, such as 2 for gases or 8 for corrosives.

Question 44Hazard communication: labels, placards, and markings

A package is labelled with a Class 6.1 toxic substance label. Which additional marking is required if the substance is also environmentally hazardous?

  1. A marine pollutant mark Correct answer.
  2. A Class 2.1 flammable gas label
  3. A Class 8 corrosive label
  4. A Class 7 radioactive label

Explanation

When a toxic substance is also environmentally hazardous, the package must carry the marine pollutant mark in addition to the Class 6.1 label. The mark communicates the aquatic hazard separately from the human toxicity hazard.

Question 45Hazard communication: labels, placards, and markings

What is the required minimum size for hazard labels on packages under the model regulations?

  1. At least 200 mm by 200 mm for all packages
  2. There is no minimum size requirement
  3. At least 50 mm by 50 mm for all packages
  4. At least 100 mm by 100 mm, with a smaller size permitted for small packages Correct answer.

Explanation

Hazard labels must be at least 100 mm on each side, although a reduced size of 50 mm is allowed for small packages where the full size cannot be applied. The size ensures the label is legible at a distance.

Question 46Hazard communication: labels, placards, and markings

A tank container is carrying a Class 2.3 toxic gas. Which placards must be displayed?

  1. A Class 2.3 placard with the UN number Correct answer.
  2. A Class 2.1 placard with the UN number
  3. A Class 6.1 placard with the UN number
  4. A Class 2.2 placard without a UN number

Explanation

Toxic gases fall under Class 2.3, so the tank container must display a Class 2.3 placard bearing the UN number of the gas. The UN number is required on placards for tank containers and tank vehicles.

Question 47Hazard communication: labels, placards, and markings

A consignor is marking a package of a substance that is hazardous to the environment but is not otherwise classified as dangerous goods. What marking is required?

  1. The marine pollutant mark only Correct answer.
  2. A Class 3 label and the UN number
  3. A Class 9 label and the UN number
  4. No marking is required because it is not dangerous goods

Explanation

Substances that are environmentally hazardous but not otherwise dangerous goods are identified by the marine pollutant mark alone. They do not receive a hazard class label unless they meet the criteria for a dangerous goods class.

Question 48Hazard communication: labels, placards, and markings

A package bears both a Class 3 flammable liquid label and a Class 8 corrosive label. What does this combination indicate?

  1. The substance has only one hazard, and the second label is an error
  2. The substance is a Class 3 substance with no subsidiary hazard
  3. The substance is a mixture of two unrelated products
  4. The substance presents both flammability and corrosivity hazards Correct answer.

Explanation

When a substance meets the criteria for more than one hazard class, it receives a primary label for its most significant hazard and subsidiary labels for the others. Two labels therefore indicate that both flammability and corrosivity hazards are present.

Question 49Hazard communication: labels, placards, and markings

What information must appear on the orange plate displayed on a road tank vehicle?

  1. The driver's name on top and the vehicle registration below
  2. The hazard identification number on top and the UN number below Correct answer.
  3. The UN number on top and the hazard identification number below
  4. The proper shipping name on top and the class number below

Explanation

The orange plate is divided horizontally: the hazard identification number is printed in the upper half and the UN number in the lower half. This fixed layout lets responders read the hazard type and substance identity consistently.

Question 50Hazard communication: labels, placards, and markings

A shipper uses a package that already bears a label for a different substance. What is the correct action before reusing the package?

  1. Add the new label next to the old one
  2. Cover the old label with the new one
  3. Remove or completely obliterate the old label before applying the new one Correct answer.
  4. Leave the old label in place to avoid damaging the package

Explanation

Old labels and markings that no longer apply must be removed or completely obliterated so they cannot mislead handlers or responders. Covering or placing a new label alongside the old one leaves conflicting information visible.