1. OSHA Laboratory Standard
Key exam domainIdentify weak areas and improve with focused review.
Start PracticingPass your CHO certification
Free CHO Practice Test
Pass the Chemical Hygiene Officer exam with confidence.
Start with a free CHO practice test and build exam-ready confidence for the Chemical Hygiene Officer exam.
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1000+CHO Questions
18Exam Domains
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Everything your CHO certification prep needs
Practice expert-vetted questions, find your weak domains, and turn every mistake into a focused review plan.
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Domain analytics show which parts of the exam blueprint are holding you back.
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Study by domain
Practice the CHO exam by domain
2. GHS labeling and classification of chemicals
Key exam domainIdentify weak areas and improve with focused review.
Start Practicing3. other pertinent regulations
Key exam domainIdentify weak areas and improve with focused review.
Start Practicing4. standard operating procedures
Key exam domainIdentify weak areas and improve with focused review.
Start Practicing5. hazard assessment
Key exam domainIdentify weak areas and improve with focused review.
Start Practicing6. safe work practices
Key exam domainIdentify weak areas and improve with focused review.
Start Practicing7. personal hygiene practices
Key exam domainIdentify weak areas and improve with focused review.
Start Practicing8. general laboratory practices
Key exam domainIdentify weak areas and improve with focused review.
Start Practicing9. special procedures (by hazard class)
Key exam domainIdentify weak areas and improve with focused review.
Start Practicing10. procedures for select carcinogens, reproductive toxins, highly toxic substances, and substances with unknown toxicity
Key exam domainIdentify weak areas and improve with focused review.
Start Practicing11. finding information sources
Key exam domainIdentify weak areas and improve with focused review.
Start Practicing12. control measures, including respirators, laboratory ventilation, and exposure monitoring
Key exam domainIdentify weak areas and improve with focused review.
Start Practicing13. employee training and information
Key exam domainIdentify weak areas and improve with focused review.
Start Practicing14. medical consultation and examination
Key exam domainIdentify weak areas and improve with focused review.
Start Practicing15. emergencies, including plans for power failure, spills, etc.
Key exam domainIdentify weak areas and improve with focused review.
Start Practicing16. laboratory visitors, contractors, maintenance personnel, etc.
Key exam domainIdentify weak areas and improve with focused review.
Start Practicing17. record keeping and documentation
Key exam domainIdentify weak areas and improve with focused review.
Start Practicing18. audits, inspections, and self-evaluations
Key exam domainIdentify weak areas and improve with focused review.
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Frequently asked questions
Straight answers about the CHO exam, the questions, pricing, the free trial, and how this fits your prep.
The CHO exam spans 18 domains - OSHA Laboratory Standard, GHS labeling and classification of chemicals, other pertinent regulations, standard operating procedures, hazard assessment, safe work practices, personal hygiene practices, general laboratory practices, special procedures (by hazard class), procedures for select carcinogens, reproductive toxins, highly toxic substances, and substances with unknown toxicity, finding information sources, control measures, including respirators, laboratory ventilation, and exposure monitoring, employee training and information, medical consultation and examination, emergencies, including plans for power failure, spills, etc., laboratory visitors, contractors, maintenance personnel, etc., record keeping and documentation, and audits, inspections, and self-evaluations. Every practice question maps to one of them, so you train on exactly what's tested.
The Chemical Hygiene Officer (CHO) exam has 150 questions and is completed in 3 hours. Our timed practice tests mirror that length and pacing, so exam day feels familiar.
No - and that matters. These are original practice questions written to mirror the style, difficulty, and domain coverage of the CHO exam blueprint. We never distribute actual exam content, so practicing here keeps you fully compliant with official exam policies.
No. CHO Exam Prep is an independent study resource for Chemical Hygiene Officer (CHO). It is not affiliated with, sponsored by, or endorsed by the official certifying body or exam administrator.
Every paid plan unlocks the full bank of 1,000+ practice questions covering all 18 CHO domains - OSHA Laboratory Standard, GHS labeling and classification of chemicals, other pertinent regulations, standard operating procedures, hazard assessment, safe work practices, personal hygiene practices, general laboratory practices, special procedures (by hazard class), procedures for select carcinogens, reproductive toxins, highly toxic substances, and substances with unknown toxicity, finding information sources, control measures, including respirators, laboratory ventilation, and exposure monitoring, employee training and information, medical consultation and examination, emergencies, including plans for power failure, spills, etc., laboratory visitors, contractors, maintenance personnel, etc., record keeping and documentation, and audits, inspections, and self-evaluations. You can practice the whole bank, filter by domain, or run a timed, domain-balanced exam simulation.
Yes - the bank is maintained against the current exam outline, and questions are revised when the exam changes.
No honest practice platform can guarantee a pass. What realistic practice does is show you - before exam day - exactly which domains are weak, and give you the repetitions to fix them. That's the difference between hoping you're ready and knowing where you stand.
Yes. You get 10 free sample questions with instant feedback - no credit card and no account required.
The free sample shows you the question quality. Paid plans unlock the full 1,000+ question bank, exam-style practice modes, mistake review, and - on Fast Track and Pass Confidence - progress analytics that show your readiness by domain.
No. Every plan is a single one-time payment for a fixed access window - 48 hours, 7 days, or 6 weeks. There is no auto-renewal and no recurring billing.
Match it to your exam date: Final Review (2 days) for an exam in the next day or two, Fast Track (7 days) for an exam this week, Pass Confidence (6 weeks) for a structured run-up.
For most countries, the price you see is exactly what you pay - tax is already included. Where local law requires it to be added separately, it's shown clearly at checkout before you pay, so there are never any surprise fees.
Access is instant after payment and runs for your plan's full window from that moment. When the window ends, your local progress stays on your device - you can buy another window any time and pick up where you left off.
Yes - the whole platform is mobile-first: practice, mistake review, and analytics all work on any phone, tablet, or laptop with a browser. Nothing to install.
Every answer feeds your per-domain accuracy, readiness score, and weak-area list. Instead of re-reading everything, you drill the domains that are actually costing you points - that's what moves a score in days, not months.
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Make sure you're signed in with the same email you used at checkout - access activates within a minute of payment. If it still doesn't appear, email us from the contact link in the footer and it'll be sorted out.
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Trusted by CHO candidates
Real feedback from CHO candidates on Reddit.
"put this off for weeks then had like 10 days left. the practice questions on choexam.com were the only reason i got thru the ventilation and exposure monitoring stuff. passed first try, still kinda shocked."
"honestly wasnt sure an online prep thing would help since my job already covers alot of this day to day. but the mistake review after each quiz pointed out gaps in stuff like select carcinogen procedures i didnt even know i had. ended up passing comfortably."
"did the mock exams twice. second time my score jumped alot once i actually slowed down on the GHS labeling questions instead of guessing. no magic trick, just reps. passed and moved on with my life."