Free QLS Practice Questions

Question 1

A laboratory adds a xylene-based preparation step to work performed in a certified Class II Type A2 biological safety cabinet. The cabinet returns its HEPA-filtered exhaust to the room. Airflow readings remain normal, but staff notice solvent odor. What should the safety officer conclude?

Accepted Answer

The cabinet lacks vapor control; the solvent step needs suitable chemical exhaust.

Answer

Replace the HEPA filters to restore their vapor-adsorption capacity.

Answer

The blower speed should be increased so that the HEPA filters capture more solvent vapor.

Answer

Fit-tested N95 respirators will address the remaining exposure because cabinet airflow is satisfactory.

Question 2

Blood from an HBsAg-positive patient splashes into an immunocompetent technologist's eye. The technologist irrigates the eye and reports for occupational-health evaluation. Records document a complete hepatitis B vaccine series and an anti-HBs concentration of 82 mIU/mL measured one month after the final dose. A repeat anti-HBs result obtained today is 4 mIU/mL. While other bloodborne risks are assessed, which HBV-specific recommendation is appropriate?

Accepted Answer

No HBV postexposure prophylaxis is indicated for this documented vaccine responder.

Answer

Give a hepatitis B booster and repeat antibody testing.

Answer

Give hepatitis B immune globulin and begin a second complete vaccine series.

Answer

Give two doses of hepatitis B immune globulin, separated by one month.

Question 3

Personal monitoring in a histology operation covered by OSHA's formaldehyde standard measures 1.2 ppm for 3 hours and 0.2 ppm for the remaining 5 hours of an 8-hour shift. Separate representative sampling of the highest-exposure 15-minute task measures 1.6 ppm. The employee has no exposure-related symptoms. Which interpretation of the 8-hour exposure and its follow-up is correct?

Accepted Answer

0.58 ppm; repeat monitoring at least every six months and offer medical surveillance.

Answer

0.70 ppm; no periodic exposure monitoring is needed because the result is below the permissible exposure limit.

Answer

0.58 ppm; suspend the procedure because the TWA permissible exposure limit is exceeded.

Answer

1.40 ppm; institute additional exposure controls because the result exceeds the 8-hour permissible exposure limit.

Question 4

Which extinguishing agent is appropriate for a fire involving magnesium turnings?

Accepted Answer

Class D dry powder rated for magnesium.

Answer

Multipurpose ABC dry chemical.

Answer

Carbon dioxide from a B:C-rated extinguisher.

Answer

Water from a pressurized Class A extinguisher.

Question 5

An autoclaved laboratory-waste load is awaiting release as treated waste. The chamber record meets the programmed time and temperature, and the external indicator tape has changed color. A correctly placed Geobacillus stearothermophilus biological indicator from within the load is positive; its controls are valid. How should this load be handled?

Accepted Answer

Quarantine the load and investigate the biological-indicator failure before release.

Answer

Release it because the chamber record and tape agree.

Answer

Release it after an empty-chamber repeat test is negative.

Answer

Clear it for disposal after testing an additional outer-surface indicator.

Question 6

A shipping coordinator prepares two separate air shipments for a reference laboratory: an unprocessed sputum specimen being tested for tuberculosis, professionally assessed as an infectious substance that does not meet Category A criteria, and a viable Mycobacterium tuberculosis culture. Under U.S. DOT classification, which UN-number pairing is correct?

Accepted Answer

Sputum: UN 3373; culture: UN 2814.

Answer

Sputum: UN 3373; culture: UN 3373.

Answer

Sputum: UN 2814; culture: UN 2814.

Answer

Sputum: UN 2814; culture: UN 3373.

Question 7

An outside service company will replace a valve on a laboratory autoclave. Both the hospital and the contractor have written lockout/tagout procedures, but their procedures differ. What coordination does OSHA require between the two employers before this work?

Accepted Answer

They exchange procedures, and the hospital ensures its employees understand and follow the contractor's restrictions.

Answer

The hospital supplies its own procedures; no exchange is needed.

Answer

The contractor supplies its employees' training certificates; those certificates replace the need to exchange operating procedures.

Answer

The hospital transfers responsibility for energy control to the contractor and excludes hospital employees from the coordination process.

Question 8

During a controlled chemical-resistance test, solvent is detected on the inner surface of a disposable glove. Integrity testing confirms that the glove has no holes or tears. There is no swelling, cracking, or softening, and the cuff has remained dry. Which mechanism accounts for the solvent crossing the barrier?

Accepted Answer

Permeation through the intact glove material.

Answer

Penetration through a defect in the glove.

Answer

Degradation of the glove's physical structure.

Answer

Wicking around the glove's open cuff.

Question 9

Following a liquid-nitrogen release, a cryogen-storage room's oxygen monitor reads 9.2%. A coworker is visible on the floor inside. Staff have activated emergency response and prevented entry. Which respiratory equipment is appropriate for a trained rescue team entering this oxygen-deficient atmosphere?

Accepted Answer

A full-face, positive-pressure self-contained breathing apparatus rated for at least 30 minutes.

Answer

An organic-vapor cartridge air-purifying respirator.

Answer

A powered air-purifying respirator fitted with high-efficiency particulate filters.

Answer

A full-face pressure-demand airline respirator connected to remote air but lacking an auxiliary escape supply.

Question 10

During one calendar month, a laboratory generates 80 kg of nonacute hazardous waste and discards 1.4 kg of a chemical product confirmed to be P-listed acute hazardous waste. There are no acute-spill residues and no applicable episodic-generation or other exemptions. Under the ordinary federal RCRA rules, which generator classification and central-accumulation time limit apply?

Accepted Answer

Large quantity generator; generally a 90-day accumulation limit.

Answer

Very small quantity generator; no fixed federal accumulation time limit.

Answer

Small quantity generator; generally a 180-day accumulation limit.

Answer

Large quantity generator; generally a 180-day accumulation limit.

Free QLS Practice Questions

Domain 1: Management (18-22%)

Question 1

Question 2

Domain 2: General Safety (18-22%)

Question 3

Question 4

Domain 3: Chemical Safety (18-22%)

Question 5

Question 6

Domain 4: Biohazard Control (18-22%)

Question 7

Question 8

Domain 5: Physical Environment (18-22%)

Question 9

Question 10

That's 10 of 1,030