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RELIAS DYSRHYTHMIA — BASIC B TEST EXAM2026 WITH
VERIFIED ANSWERS DETAILED RATIONALES GRADED A+
Relias Dysrhythmia — Basic B Test Exam
Cardiac Rhythm Interpretation
SECTION 1: ECG BASICS & MEASUREMENT (Questions 1–30)
1. What is the standard duration of one small box on an ECG grid?
A. 0.01 seconds
B. 0.04 seconds
C. 0.12 seconds
D. 0.20 seconds
Correct Answer: B) 0.04 seconds
Rationale: On standard ECG graph paper, a single small box measures 1 mm by 1 mm and
represents 0.04 seconds horizontally. This knowledge is essential for calculating heart rates and
measuring intervals using the "count the boxes" method. The paper speed is standard at 25
mm/second.
2. What is the standard duration of one large box on an ECG grid?
A. 0.04 seconds
B. 0.12 seconds
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C. 0.20 seconds
D. 0.40 seconds
Correct Answer: C) 0.20 seconds
Rationale: A large box consists of 5 small boxes horizontally. Multiplying 5 by 0.04 seconds
yields 0.20 seconds. Large boxes are used for quick rate calculations (300, 150, 100, 75, 60, 50
method) and interval measurements.
3. A normal PR interval measures between which time frames?
A. 0.04 to 0.10 seconds
B. 0.12 to 0.20 seconds
C. 0.20 to 0.35 seconds
D. 0.35 to 0.44 seconds
Correct Answer: B) 0.12 to 0.20 seconds
Rationale: A normal PR interval is between 3 and 5 small boxes wide, which translates to 0.12 to
0.20 seconds. Anything longer indicates a conduction delay in the AV node or His-Purkinje
system. PR interval is measured from the beginning of the P wave to the beginning of the QRS
complex.
4. Which measurement represents a normal, non-widened QRS complex duration?
A. Less than 0.12 seconds
B. 0.12 to 0.20 seconds
C. 0.20 to 0.35 seconds
D. Greater than 0.35 seconds
Correct Answer: A) Less than 0.12 seconds
Rationale: The QRS complex reflects ventricular depolarization. It is normally narrow (0.06–0.12
seconds). A widened QRS may indicate a ventricular origin or conduction delay through the
bundle branches or Purkinje fibers.
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5. What is the primary function of the AV node?
A. Initiate the heartbeat
B. Rapidly conduct impulses to the ventricles
C. Slow the impulse to allow ventricular filling
D. Depolarize the Purkinje fibers
Correct Answer: C) Slow the impulse to allow ventricular filling
Rationale: The AV node delays the electrical impulse slightly, allowing the atria time to contract
and complete ventricular filling before ventricular depolarization occurs. This delay is essential
for efficient cardiac function.
6. The T wave on an ECG represents:
A. Atrial depolarization
B. Ventricular depolarization
C. Ventricular repolarization
D. Atrial repolarization
Correct Answer: C) Ventricular repolarization
Rationale: The T wave represents ventricular repolarization, the recovery phase of the
ventricles. It follows the QRS complex and precedes the next P wave. Abnormal T waves can
indicate ischemia, electrolyte imbalances, or other cardiac pathology.
7. A QRS duration of 0.14 seconds indicates:
A. Normal ventricular conduction
B. Delayed ventricular conduction (intraventricular conduction delay)
C. Atrial enlargement
D. Normal atrial conduction
Correct Answer: B) Delayed ventricular conduction (intraventricular conduction delay)
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Rationale: A QRS duration greater than 0.12 seconds indicates delayed ventricular conduction,
which may be due to bundle branch block, ventricular origin of the rhythm, or other conduction
abnormalities.
8. What is the normal heart rate range for a sinus rhythm in adults?
A. 40–60 bpm
B. 60–100 bpm
C. 100–120 bpm
D. 120–140 bpm
Correct Answer: B) 60–100 bpm
Rationale: Normal sinus rhythm in adults is defined as a heart rate between 60–100 beats per
minute. This rate represents appropriate SA node function with normal conduction through the
AV node and ventricular tissue. Rates below 60 (bradycardia) or above 100 (tachycardia) are
considered abnormal and require further evaluation.
9. What is the standard paper speed for ECG recording?
A. 10 mm/second
B. 15 mm/second
C. 25 mm/second
D. 50 mm/second
Correct Answer: C) 25 mm/second
Rationale: The standard ECG paper speed is 25 mm/second. At this speed, one small box (1
mm) equals 0.04 seconds, and one large box (5 mm) equals 0.20 seconds.
10. Which of the following represents a normal QRS duration?
A. 0.04–0.10 seconds
B. 0.12–0.20 seconds
C. 0.20–0.35 seconds
D. 0.35–0.44 seconds
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RELIAS DYSRHYTHMIA — BASIC B TEST EXAM2026 WITH
VERIFIED ANSWERS DETAILED RATIONALES GRADED A+
Relias Dysrhythmia — Basic B Test Exam
Cardiac Rhythm Interpretation
SECTION 1: ECG BASICS & MEASUREMENT (Questions 1–30)
1. What is the standard duration of one small box on an ECG grid?
A. 0.01 seconds
B. 0.04 seconds
C. 0.12 seconds
D. 0.20 seconds
Correct Answer: B) 0.04 seconds
Rationale: On standard ECG graph paper, a single small box measures 1 mm by 1 mm and
represents 0.04 seconds horizontally. This knowledge is essential for calculating heart rates and
measuring intervals using the "count the boxes" method. The paper speed is standard at 25
mm/second.
2. What is the standard duration of one large box on an ECG grid?
A. 0.04 seconds
B. 0.12 seconds
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C. 0.20 seconds
D. 0.40 seconds
Correct Answer: C) 0.20 seconds
Rationale: A large box consists of 5 small boxes horizontally. Multiplying 5 by 0.04 seconds
yields 0.20 seconds. Large boxes are used for quick rate calculations (300, 150, 100, 75, 60, 50
method) and interval measurements.
3. A normal PR interval measures between which time frames?
A. 0.04 to 0.10 seconds
B. 0.12 to 0.20 seconds
C. 0.20 to 0.35 seconds
D. 0.35 to 0.44 seconds
Correct Answer: B) 0.12 to 0.20 seconds
Rationale: A normal PR interval is between 3 and 5 small boxes wide, which translates to 0.12 to
0.20 seconds. Anything longer indicates a conduction delay in the AV node or His-Purkinje
system. PR interval is measured from the beginning of the P wave to the beginning of the QRS
complex.
4. Which measurement represents a normal, non-widened QRS complex duration?
A. Less than 0.12 seconds
B. 0.12 to 0.20 seconds
C. 0.20 to 0.35 seconds
D. Greater than 0.35 seconds
Correct Answer: A) Less than 0.12 seconds
Rationale: The QRS complex reflects ventricular depolarization. It is normally narrow (0.06–0.12
seconds). A widened QRS may indicate a ventricular origin or conduction delay through the
bundle branches or Purkinje fibers.
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5. What is the primary function of the AV node?
A. Initiate the heartbeat
B. Rapidly conduct impulses to the ventricles
C. Slow the impulse to allow ventricular filling
D. Depolarize the Purkinje fibers
Correct Answer: C) Slow the impulse to allow ventricular filling
Rationale: The AV node delays the electrical impulse slightly, allowing the atria time to contract
and complete ventricular filling before ventricular depolarization occurs. This delay is essential
for efficient cardiac function.
6. The T wave on an ECG represents:
A. Atrial depolarization
B. Ventricular depolarization
C. Ventricular repolarization
D. Atrial repolarization
Correct Answer: C) Ventricular repolarization
Rationale: The T wave represents ventricular repolarization, the recovery phase of the
ventricles. It follows the QRS complex and precedes the next P wave. Abnormal T waves can
indicate ischemia, electrolyte imbalances, or other cardiac pathology.
7. A QRS duration of 0.14 seconds indicates:
A. Normal ventricular conduction
B. Delayed ventricular conduction (intraventricular conduction delay)
C. Atrial enlargement
D. Normal atrial conduction
Correct Answer: B) Delayed ventricular conduction (intraventricular conduction delay)
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Rationale: A QRS duration greater than 0.12 seconds indicates delayed ventricular conduction,
which may be due to bundle branch block, ventricular origin of the rhythm, or other conduction
abnormalities.
8. What is the normal heart rate range for a sinus rhythm in adults?
A. 40–60 bpm
B. 60–100 bpm
C. 100–120 bpm
D. 120–140 bpm
Correct Answer: B) 60–100 bpm
Rationale: Normal sinus rhythm in adults is defined as a heart rate between 60–100 beats per
minute. This rate represents appropriate SA node function with normal conduction through the
AV node and ventricular tissue. Rates below 60 (bradycardia) or above 100 (tachycardia) are
considered abnormal and require further evaluation.
9. What is the standard paper speed for ECG recording?
A. 10 mm/second
B. 15 mm/second
C. 25 mm/second
D. 50 mm/second
Correct Answer: C) 25 mm/second
Rationale: The standard ECG paper speed is 25 mm/second. At this speed, one small box (1
mm) equals 0.04 seconds, and one large box (5 mm) equals 0.20 seconds.
10. Which of the following represents a normal QRS duration?
A. 0.04–0.10 seconds
B. 0.12–0.20 seconds
C. 0.20–0.35 seconds
D. 0.35–0.44 seconds
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