Chem Lab Quiz
Questions: 16 · 10 minutes
1. You need to read the volume of a clear aqueous liquid in a graduated cylinder. What is the usual correct approach?
Read the top of the meniscus while looking down into the cylinder
Place your eyes level with the liquid and read the bottom of the meniscus
Tilt the cylinder until the liquid surface appears flat
Read where the liquid touches the cylinder wall at its highest point
2. While heating liquid in a test tube, which position best protects nearby people?
Hold the tube vertically so any liquid remains near the bottom
Hold the tube at an angle with its opening pointed away from everyone
Stopper the tube loosely to reduce evaporation
Point the opening toward the empty section of your own workbench
3. An experiment produces a mixture of aqueous chemical waste, and you are not certain which waste stream accepts it. What should you do?
Keep it contained and labeled, then consult the procedure, waste guidance, or supervisor before disposal
Add it to the largest available liquid-waste bottle
Leave it in an unlabeled beaker for someone else to identify
Pour it down the drain while flushing with plenty of water
4. A procedure specifically instructs you to assess the odor of a chemical. How should you do it?
Keep the container at a distance and gently waft vapor toward your nose
Shake the closed container and smell near its cap
Smell directly above the open container for only a moment
Transfer some chemical to a watch glass so more vapor is released
5. Which item is generally best for transferring one specified volume, such as exactly 25.00 mL, with high accuracy?
A 50 mL beaker
A 50 mL graduated cylinder
A 25 mL volumetric pipette used with a pipette aid
A disposable dropper marked at 1 mL intervals
6. A person's laboratory coat and clothing catch fire. Which response is generally appropriate in an equipped chemistry lab?
Run to the nearest exit before attempting to extinguish the flames
Remove the coat while continuing to hold any chemical container involved
Use the safety shower promptly while others alert the supervisor and emergency response
Use a carbon dioxide extinguisher directly on the person's upper body
7. A reaction produces an insoluble solid suspended in a liquid. Which technique is commonly used to separate and collect the solid?
Simple distillation
Titration
Filtration
Volumetric dilution
8. When preparing a dilute aqueous acid solution from concentrated acid, which procedure is appropriate?
Add water rapidly to the measured acid so the mixture cools quickly
Slowly add the acid to the water while stirring and following the specified protective measures
Mix equal portions of acid and water before adjusting the final volume
Combine the liquids in a sealed container to contain any vapor
9. You are working with a volatile solvent in a functioning fume hood. Which setup is appropriate?
Turn off the hood fan while pouring to prevent turbulence
Raise the sash fully so your arms can move without restriction
Place all apparatus directly against the front edge for easier access
Keep the sash at the indicated height and perform the work well inside the hood
10. A chemical splashes into a student's eye. What should the student do first?
Use the eyewash immediately, hold the eyelids open, and rinse continuously for the required time while help is alerted
Wipe the eye with a clean paper towel before checking the chemical label
Apply neutralizing solution to counteract the chemical
Keep the eye closed while another person searches for the instructor
11. A beaker breaks on the laboratory floor. Where should the glass be discarded after the area is secured?
In the designated broken-glass or sharps container, using suitable tools rather than bare hands
In the chemical-waste container used for liquid reagents
In the nearest sink after breaking it into smaller pieces
In the regular trash after wrapping it in paper towels
12. You need to run one sample tube in a laboratory centrifuge. How should the rotor usually be prepared?
Place the sample near the center of the rotor to reduce its motion
Use a higher speed so the rotor passes quickly through any vibration
Put an empty tube opposite the sample regardless of the sample's mass
Place a tube of equal mass directly opposite the sample tube
13. You dispense more solid reagent than your experiment requires. What should you do with the excess?
Dissolve it in water so it can be poured into a liquid-waste bottle
Return it to the stock bottle if its appearance has not changed
Leave it on weighing paper beside the stock container
Place it in the designated waste container rather than returning it to the stock bottle
14. Which label is most appropriate for a solution you have prepared for later laboratory use?
The solution's abbreviation and your initials only
The experiment number and the color of the solution
The name of the original stock chemical without dilution details
Its identity, concentration where relevant, hazard information, preparation date, and responsible person's identification
15. Before use, you notice that an electrical hot plate has a frayed power cord with exposed wiring. What is the appropriate response?
Cover the damaged section with a paper towel and keep it dry
Do not use it; disconnect it if that can be done safely and report or tag the equipment according to lab procedure
Move the hot plate into a fume hood before plugging it in
Use the hot plate only at its lowest temperature setting
16. A crucible has just been strongly heated and must be weighed accurately. What should happen before weighing?
Place it on the balance immediately with crucible tongs
Allow it to stand on the balance pan until the reading stabilizes
Let it cool to the required temperature in a desiccator, then weigh it according to the procedure
Cool it uncovered beside the balance so air circulates around it