HOSA EKG EXAM QUESTIONS AND ANSWERS

HOSA EKG EXAM QUESTIONS AND ANSWERS
 Course
 HOSA EKG

1. Which wave on the ECG represents atrial depolarization?

A. T wave
B. QRS complex
C. P wave
D. U wave

✅ Correct Answer: C. P wave
Rationale: The P wave represents atrial depolarization, which is the electrical activation of the
atria preceding contraction. The QRS complex represents ventricular depolarization, and the T
wave represents ventricular repolarization.



2. What is the normal duration of the PR interval in an adult ECG?

A. 0.06–0.10 seconds
B. 0.12–0.20 seconds
C. 0.20–0.30 seconds
D. 0.30–0.40 seconds

✅ Correct Answer: B. 0.12–0.20 seconds
Rationale: A normal PR interval lasts 0.12 to 0.20 seconds, representing the time it takes for
the electrical impulse to travel from the atria to the ventricles via the AV node.



3. What does a wide QRS complex (>0.12 seconds) typically indicate?

A. Sinus tachycardia
B. Normal conduction
C. Bundle branch block or ventricular origin rhythm
D. Atrial fibrillation

✅ Correct Answer: C. Bundle branch block or ventricular origin rhythm
Rationale: A wide QRS suggests delayed ventricular conduction, which can be caused by a
bundle branch block or a ventricular ectopic beat.

,4. Which lead is most commonly used for rhythm monitoring in continuous
telemetry?

A. Lead I
B. Lead II
C. Lead aVR
D. Lead V6

✅ Correct Answer: B. Lead II
Rationale: Lead II provides the clearest view of the heart's rhythm, especially the P wave, due
to its alignment with the heart’s electrical axis.



5. What heart rate corresponds to five large boxes between R waves on an ECG?

A. 60 bpm
B. 75 bpm
C. 100 bpm
D. 50 bpm

✅ Correct Answer: A. 60 bpm
Rationale: In a regular rhythm, each large box = 0.2 seconds. Five large boxes = 1 second →
60 beats per minute (60 seconds ÷ 1 second per beat).



6. Which rhythm is characterized by a chaotic baseline and no discernible P
waves?

A. Atrial flutter
B. Atrial fibrillation
C. Ventricular tachycardia
D. Normal sinus rhythm

✅ Correct Answer: B. Atrial fibrillation
Rationale: Atrial fibrillation shows irregular R-R intervals, absent P waves, and a
fibrillatory baseline, indicating erratic atrial activity.



7. What is the appropriate action for a flatline (asystole) seen on the ECG?

A. Defibrillate immediately
B. Check for pulse, start CPR, and confirm in two leads

, C. Administer adenosine
D. Perform synchronized cardioversion

✅ Correct Answer: B. Check for pulse, start CPR, and confirm in two leads
Rationale: Asystole is a non-shockable rhythm. First, confirm it in two leads, then start CPR
and administer epinephrine, not defibrillation.



8. What condition is suggested by ST segment elevation in multiple contiguous
leads?

A. Atrial fibrillation
B. Myocardial infarction
C. Sinus bradycardia
D. First-degree AV block

✅ Correct Answer: B. Myocardial infarction
Rationale: ST elevation in contiguous leads is a hallmark of acute myocardial infarction,
indicating full-thickness cardiac muscle injury.



9. What is the paper speed of standard ECG recording?

A. 5 mm/sec
B. 10 mm/sec
C. 25 mm/sec
D. 50 mm/sec

✅ Correct Answer: C. 25 mm/sec
Rationale: Standard ECGs are recorded at 25 mm/sec. Each small square represents 0.04
seconds, and each large square represents 0.2 seconds.



10. Which electrolyte imbalance is most likely to cause peaked T waves on ECG?

A. Hypokalemia
B. Hyperkalemia
C. Hypercalcemia
D. Hyponatremia

✅ Correct Answer: B. Hyperkalemia
Rationale: Hyperkalemia leads to tall, peaked T waves, widening of QRS, and eventually sine
wave pattern if untreated. It is a cardiac emergency.