Test with Verified Answers
This practice test contains 150 questions with verified answers and detailed
rationales, designed to help you master cardiac rhythm recognition, ECG
interpretation, and prepare confidently for the Relias Dysrhythmia Basic A Exam .
Questions 1-20
Q1. What does the horizontal axis on an ECG measure?
A) Voltage
B) Time
C) Amplitude
D) Resistance
Answer: B) Time
Rationale: The horizontal axis on ECG paper represents time. At standard paper speed
(25 mm/sec), each small box equals 0.04 seconds, and each large box equals 0.20
seconds .
Q2. How many seconds does one large box represent on standard ECG paper?
A) 0.04 seconds
B) 0.20 seconds
C) 0.10 seconds
D) 1.00 seconds
Answer: B) 0.20 seconds
,Rationale: One large box consists of five small boxes, each representing 0.04 seconds,
for a total of 0.20 seconds .
Q3. What is the duration of one small box on standard ECG paper?
A) 0.04 seconds
B) 0.20 seconds
C) 0.10 seconds
D) 0.01 seconds
Answer: A) 0.04 seconds
Rationale: Each small box on the horizontal axis represents 0.04 seconds at standard
paper speed .
Q4. What voltage does one small box on the vertical axis represent?
A) 0.1 mV
B) 0.5 mV
C) 1.0 mV
D) 0.01 mV
Answer: A) 0.1 mV
Rationale: Vertically, each small box on standard ECG paper represents 0.1 millivolts of
amplitude .
Q5. What is the standard paper speed for an ECG recording?
A) 10 mm/sec
B) 25 mm/sec
C) 50 mm/sec
D) 100 mm/sec
,Answer: B) 25 mm/sec
Rationale: The standard recording speed for an ECG is 25 mm per second .
Q6. Where is the SA node located?
A) Left atrium
B) Right atrium
C) Left ventricle
D) Interventricular septum
Answer: B) Right atrium
Rationale: The sinoatrial (SA) node is located in the upper wall of the right atrium. It
serves as the primary pacemaker of the heart .
Q7. Where is the AV node located?
A) Floor of the right atrium
B) Apex of the right ventricle
C) Interventricular septum
D) Left atrium
Answer: A) Floor of the right atrium
Rationale: The atrioventricular (AV) node is located in the floor of the right atrium near
the interatrial septum .
Q8. What structure directly follows the AV node in the conduction pathway?
A) Bundle branches
B) Purkinje fibers
, C) Bundle of His
D) Internodal pathways
Answer: C) Bundle of His
Rationale: The electrical impulse travels from the AV node to the Bundle of His before
dividing into the left and right bundle branches .
Q9. What is the normal intrinsic firing rate of the SA node?
A) 20-40 bpm
B) 40-60 bpm
C) 60-100 bpm
D) 100-150 bpm
Answer: C) 60-100 bpm
Rationale: The SA node naturally fires at a rate of 60 to 100 beats per minute. It is the
primary pacemaker due to its highest intrinsic rate .
Q10. What is the normal intrinsic firing rate of the AV junction?
A) 20-40 bpm
B) 40-60 bpm
C) 60-100 bpm
D) 100-150 bpm
Answer: B) 40-60 bpm
Rationale: The AV junction has an intrinsic rate of 40 to 60 beats per minute .
Q11. What is the normal intrinsic firing rate of the ventricles?