Educational information only — not a diagnosis. Always talk to a qualified doctor.
LabologicsUnderstand your labs اردو

Exam Prep

Lab Safety & Waste practice questions.

Fire, chemical and electrical safety, biosafety, PPE and exposures, disinfection and waste disposal.

All subjects

Independent practice questions written by Labologics. Not affiliated with DHA, DOH (formerly HAAD), SCFHS, Prometric or any exam body. Not recalled exam questions.

Fire safety

Q1 Fire safety · Easy

In the RACE fire response, the first step is:

  1. A: Rescue anyone in immediate danger
  2. B: Contain
  3. C: Extinguish
  4. D: Alarm
Show answer

Answer: A — Rescue anyone in immediate danger

RACE = Rescue, Alarm (activate the alarm), Contain (close doors), Extinguish if small or Evacuate.

Reference: OSHA laboratory and bloodborne pathogens standards

Q2 Fire safety · Easy

PASS for using a fire extinguisher stands for:

  1. A: Push, Aim, Spray, Stop
  2. B: Pull, Aim, Squeeze, Sweep
  3. C: Pull, Alert, Spray, Shut
  4. D: Point, Aim, Squeeze, Step
Show answer

Answer: B — Pull, Aim, Squeeze, Sweep

Aim at the base of the fire, not the flames.

Reference: OSHA laboratory and bloodborne pathogens standards

Q3 Fire safety · Medium

An electrical analyzer catches fire. The safest extinguisher is:

  1. A: Wet blanket soaked in water
  2. B: Water
  3. C: Carbon dioxide (CO2) or dry chemical, after cutting power if safe
  4. D: Foam
Show answer

Answer: C — Carbon dioxide (CO2) or dry chemical, after cutting power if safe

Water conducts electricity. Electrical fires are class C (US) or class E in some systems.

Reference: OSHA laboratory and bloodborne pathogens standards

Q4 Fire safety · Easy

A fire is spreading to the ceiling in a closed room. The best action is:

  1. A: Open windows
  2. B: Collect your samples first
  3. C: Fight it with one extinguisher
  4. D: Leave, close the door to contain it, activate the alarm and evacuate
Show answer

Answer: D — Leave, close the door to contain it, activate the alarm and evacuate

Only attempt to extinguish small fires with a clear escape route.

Reference: OSHA laboratory and bloodborne pathogens standards

Q5 Fire safety · Medium

In the NFPA 704 diamond, the red section shows:

  1. A: Flammability
  2. B: Instability / reactivity
  3. C: Special hazards
  4. D: Health hazard
Show answer

Answer: A — Flammability

Blue = health, red = flammability, yellow = instability, white = special (e.g., OX, W). Ratings run 0 (minimal) to 4 (severe).

Reference: OSHA laboratory and bloodborne pathogens standards

Chemical safety

Q6 Chemical safety · Easy

Information on a chemical's hazards, safe handling and spill response is found in the:

  1. A: Package insert
  2. B: Safety Data Sheet (SDS)
  3. C: Procedure log
  4. D: Invoice
Show answer

Answer: B — Safety Data Sheet (SDS)

SDS must be kept where all staff can reach them quickly.

Reference: OSHA laboratory and bloodborne pathogens standards

Q7 Chemical safety · Easy

A small acid spill is neutralized with:

  1. A: Ethanol
  2. B: Weak acid
  3. C: Sodium bicarbonate (from an acid spill kit)
  4. D: Water only
Show answer

Answer: C — Sodium bicarbonate (from an acid spill kit)

Alkali spills are neutralized with a weak acid (e.g., citric acid).

Reference: OSHA laboratory and bloodborne pathogens standards

Q8 Chemical safety · Medium

A large chemical spill (e.g., 2 L) with a strong, suffocating smell. The correct action is:

  1. A: Add water to dilute it
  2. B: Continue working with a mask
  3. C: Clean it with paper towels
  4. D: Evacuate the area, prevent entry and call the safety officer / emergency team
Show answer

Answer: D — Evacuate the area, prevent entry and call the safety officer / emergency team

Small spills can be contained and cleaned by trained staff with proper PPE; large or hazardous spills need the emergency team.

Reference: OSHA laboratory and bloodborne pathogens standards

Q9 Chemical safety · Easy

A chemical splashes into a technologist's eye. The first action is:

  1. A: Flush the eye at an eyewash station for at least 15 minutes, then get medical care
  2. B: Rub the eye
  3. C: Neutralize with acid
  4. D: Apply eye drops
Show answer

Answer: A — Flush the eye at an eyewash station for at least 15 minutes, then get medical care

Remove contact lenses if easy to do so.

Reference: OSHA laboratory and bloodborne pathogens standards

Q10 Chemical safety · Medium

Formaldehyde is hazardous because it is:

  1. A: Radioactive
  2. B: An irritant, sensitizer and known human carcinogen
  3. C: Explosive when dry
  4. D: Harmless
Show answer

Answer: B — An irritant, sensitizer and known human carcinogen

OSHA limits: 0.75 ppm over 8 hours (TWA) and 2 ppm over 15 minutes (STEL). Use fume hoods and monitor exposure.

Reference: OSHA laboratory and bloodborne pathogens standards

Q11 Chemical safety · Medium

Picric acid becomes dangerous when it:

  1. A: Is diluted
  2. B: Gets wet
  3. C: Dries out (it can explode)
  4. D: Is refrigerated
Show answer

Answer: C — Dries out (it can explode)

Keep it wet and check stock regularly.

Reference: OSHA laboratory and bloodborne pathogens standards

Q12 Chemical safety · Hard

Reagents containing sodium azide should not be poured down drains because:

  1. A: They are radioactive
  2. B: They are flammable
  3. C: They clog pipes
  4. D: Azide reacts with lead or copper plumbing to form explosive metal azides
Show answer

Answer: D — Azide reacts with lead or copper plumbing to form explosive metal azides

Dispose of them as chemical waste according to local rules.

Reference: OSHA laboratory and bloodborne pathogens standards

Q13 Chemical safety · Medium

Flammable liquids like xylene and ethanol should be stored:

  1. A: In an approved flammable storage cabinet, away from heat and oxidizers
  2. B: In the refrigerator used for food
  3. C: In a fume hood forever
  4. D: On open shelves near the bench
Show answer

Answer: A — In an approved flammable storage cabinet, away from heat and oxidizers

Only explosion-proof (flammable-safe) refrigerators should store flammable chemicals.

Reference: OSHA laboratory and bloodborne pathogens standards

Q14 Chemical safety · Easy

The main routes of chemical exposure are:

  1. A: Only inhalation
  2. B: Inhalation, ingestion, skin and eye contact, and injection
  3. C: Only skin contact
  4. D: Only ingestion
Show answer

Answer: B — Inhalation, ingestion, skin and eye contact, and injection

PPE and fume hoods block these routes.

Reference: OSHA laboratory and bloodborne pathogens standards

Biosafety

Q15 Biosafety · Easy

Standard precautions mean:

  1. A: Disinfect only at the end of the week
  2. B: Treat only known HIV samples as infectious
  3. C: Treat all blood and body fluids as potentially infectious
  4. D: Wear gloves only for TB samples
Show answer

Answer: C — Treat all blood and body fluids as potentially infectious

Standard precautions protect against unrecognized infections.

Reference: OSHA laboratory and bloodborne pathogens standards

Q16 Biosafety · Easy

The single most important way to prevent spread of infection is:

  1. A: Using a mask
  2. B: Taking antibiotics
  3. C: Wearing two pairs of gloves
  4. D: Hand hygiene
Show answer

Answer: D — Hand hygiene

Wash hands after removing gloves and before leaving the lab.

Reference: WHO Laboratory Biosafety Manual, 4th edition

Q17 Biosafety · Medium

Routine diagnostic work on clinical specimens from HIV or hepatitis B patients is performed at:

  1. A: BSL-2 with standard precautions
  2. B: BSL-4
  3. C: No containment
  4. D: BSL-1
Show answer

Answer: A — BSL-2 with standard precautions

Culturing or concentrating HIV in large volumes needs higher containment.

Reference: CDC/NIH: Biosafety in Microbiological and Biomedical Laboratories (BMBL)

Q18 Biosafety · Medium

Culturing Mycobacterium tuberculosis requires:

  1. A: BSL-2 open bench
  2. B: BSL-3 (or enhanced containment) with work in a biosafety cabinet
  3. C: No special precautions
  4. D: BSL-1
Show answer

Answer: B — BSL-3 (or enhanced containment) with work in a biosafety cabinet

TB spreads by aerosols. Smear preparation can be done in BSL-2 with a BSC, based on risk assessment.

Reference: CDC/NIH: Biosafety in Microbiological and Biomedical Laboratories (BMBL)

Q19 Biosafety · Medium

The biosafety level for a lab activity is chosen mainly based on:

  1. A: The cost of equipment
  2. B: The sample tube color
  3. C: A risk assessment of the agent and the procedure (e.g., aerosol risk)
  4. D: The number of staff
Show answer

Answer: C — A risk assessment of the agent and the procedure (e.g., aerosol risk)

The WHO 4th edition manual emphasizes risk-based biosafety.

Reference: WHO Laboratory Biosafety Manual, 4th edition

Q20 Biosafety · Medium

A Class II biological safety cabinet protects:

  1. A: Only the environment
  2. B: Nothing; it only gives light
  3. C: Only the sample
  4. D: The worker, the sample and the environment, using HEPA filters
Show answer

Answer: D — The worker, the sample and the environment, using HEPA filters

Class I protects worker and environment but not the sample. A laminar flow clean bench protects only the product and must not be used for infectious material.

Reference: CDC/NIH: Biosafety in Microbiological and Biomedical Laboratories (BMBL)

Q21 Biosafety · Medium

A tube breaks inside a closed centrifuge. The correct action is:

  1. A: Keep the lid closed for about 30 minutes to let aerosols settle, then clean with PPE and disinfectant
  2. B: Restart the centrifuge
  3. C: Spray water inside
  4. D: Open immediately to clean
Show answer

Answer: A — Keep the lid closed for about 30 minutes to let aerosols settle, then clean with PPE and disinfectant

Use sealed buckets (safety cups) for infectious samples.

Reference: WHO Laboratory Biosafety Manual, 4th edition

Q22 Biosafety · Easy

Which practice is prohibited in the laboratory?

  1. A: Using pipette aids
  2. B: Mouth pipetting, eating, drinking and applying cosmetics
  3. C: Wearing lab coats
  4. D: Labeling reagents
Show answer

Answer: B — Mouth pipetting, eating, drinking and applying cosmetics

These practices allow ingestion of infectious or toxic material.

Reference: WHO Laboratory Biosafety Manual, 4th edition

PPE & exposures

Q23 PPE & exposures · Easy

Gloves used when handling blood mainly protect against:

  1. A: Fire
  2. B: Radiation
  3. C: Blood and body fluid contact
  4. D: Heat
Show answer

Answer: C — Blood and body fluid contact

Use nitrile gloves for people with latex allergy.

Reference: OSHA laboratory and bloodborne pathogens standards

Q24 PPE & exposures · Medium

When removing PPE, which item is usually removed first because it is the most contaminated?

  1. A: Goggles
  2. B: Shoes
  3. C: Mask
  4. D: Gloves
Show answer

Answer: D — Gloves

Follow your facility's doffing sequence, and perform hand hygiene afterward.

Reference: WHO Laboratory Biosafety Manual, 4th edition

Q25 PPE & exposures · Easy

After a needlestick injury, the first action is:

  1. A: Wash the area with soap and water, then report immediately for risk assessment and possible PEP
  2. B: Wait until the end of the shift
  3. C: Take antibiotics
  4. D: Squeeze the wound and apply bleach
Show answer

Answer: A — Wash the area with soap and water, then report immediately for risk assessment and possible PEP

HIV PEP works best when started as early as possible (ideally within hours, no later than 72 hours).

Reference: OSHA laboratory and bloodborne pathogens standards

Q26 PPE & exposures · Medium

After a needlestick from an HBsAg-positive source, a key test on the exposed worker is:

  1. A: HBeAg
  2. B: Anti-HBs (to check vaccine immunity)
  3. C: Anti-HCV
  4. D: Liver biopsy
Show answer

Answer: B — Anti-HBs (to check vaccine immunity)

Non-immune workers may need HBV immunoglobulin and vaccination.

Reference: OSHA laboratory and bloodborne pathogens standards

Q27 PPE & exposures · Easy

Which vaccine is recommended for all laboratory staff handling blood?

  1. A: Cholera
  2. B: Rabies
  3. C: Hepatitis B
  4. D: Yellow fever
Show answer

Answer: C — Hepatitis B

Check the anti-HBs response after the vaccine series.

Reference: OSHA laboratory and bloodborne pathogens standards

Disinfection & waste

Q28 Disinfection & waste · Medium

A blood spill is usually disinfected with sodium hypochlorite at about:

  1. A: 50%
  2. B: Undiluted ethanol only
  3. C: 0.0001%
  4. D: 0.5% (about 5,000 ppm available chlorine), freshly prepared
Show answer

Answer: D — 0.5% (about 5,000 ppm available chlorine), freshly prepared

Absorb the spill, apply disinfectant, allow contact time, then clean.

Reference: WHO Laboratory Biosafety Manual, 4th edition

Q29 Disinfection & waste · Medium

Standard autoclave conditions are:

  1. A: 100 C for 5 minutes
  2. B: 121 C at about 15 psi for at least 15 minutes (longer for waste loads)
  3. C: 60 C for 1 hour
  4. D: 180 C dry heat for 5 minutes
Show answer

Answer: B — 121 C at about 15 psi for at least 15 minutes (longer for waste loads)

Waste loads often need 30-60 minutes. Steam must reach the whole load.

Reference: WHO Laboratory Biosafety Manual, 4th edition

Q30 Disinfection & waste · Medium

Autoclave effectiveness is checked with spores of:

  1. A: Bacillus anthracis
  2. B: Geobacillus stearothermophilus
  3. C: E. coli
  4. D: Clostridium tetani
Show answer

Answer: B — Geobacillus stearothermophilus

Chemical indicator tape shows only that heat was applied, not that sterilization was achieved.

Reference: WHO Laboratory Biosafety Manual, 4th edition

Q31 Disinfection & waste · Easy

Used needles should be:

  1. A: Bent before disposal
  2. B: Recapped with two hands
  3. C: Placed directly into a puncture-proof sharps container, closed when about 3/4 full
  4. D: Put in the regular trash
Show answer

Answer: C — Placed directly into a puncture-proof sharps container, closed when about 3/4 full

Never recap with two hands.

Reference: WHO: Safe management of wastes from health-care activities

Q32 Disinfection & waste · Medium

In the WHO color system, infectious waste goes into:

  1. A: Blue bags
  2. B: Green bags
  3. C: Black bags
  4. D: Yellow bags/containers
Show answer

Answer: D — Yellow bags/containers

General (non-hazardous) waste goes in black. Countries set their own codes, so follow national rules.

Reference: WHO: Safe management of wastes from health-care activities

Q33 Disinfection & waste · Medium

Anatomical waste (human tissue) is managed as:

  1. A: Hazardous (pathological) waste, usually incinerated or buried per national rules
  2. B: Recyclable waste
  3. C: Chemical waste only
  4. D: General waste
Show answer

Answer: A — Hazardous (pathological) waste, usually incinerated or buried per national rules

Segregate at the point of generation.

Reference: WHO: Safe management of wastes from health-care activities

Electrical & general

Q34 Electrical & general · Easy

A colleague is being shocked by faulty equipment. The first action is:

  1. A: Pull them away with your hands
  2. B: Turn off the power at the source (or use a non-conductive object), then give first aid
  3. C: Throw water on them
  4. D: Call IT
Show answer

Answer: B — Turn off the power at the source (or use a non-conductive object), then give first aid

Touching them while the current is flowing can electrocute you too.

Reference: OSHA laboratory and bloodborne pathogens standards

Q35 Electrical & general · Easy

Lab equipment should be plugged into:

  1. A: Ungrounded outlets
  2. B: Daisy-chained multi-plug adaptors
  3. C: Grounded (three-pin) outlets, without overloading
  4. D: Any outlet with a long extension cord
Show answer

Answer: C — Grounded (three-pin) outlets, without overloading

Overloaded adaptors are a fire hazard. Report damaged cords.

Reference: OSHA laboratory and bloodborne pathogens standards

Q36 Electrical & general · Medium

Compressed gas cylinders should be:

  1. A: Stored near heaters
  2. B: Rolled by the valve
  3. C: Laid on the floor
  4. D: Secured upright with a chain or strap, with the valve cap on when not in use
Show answer

Answer: D — Secured upright with a chain or strap, with the valve cap on when not in use

A broken valve can turn a cylinder into a projectile.

Reference: OSHA laboratory and bloodborne pathogens standards