220-1101 Mobile Devices Practice Question
A user reports that their smartphone's screen appears to be slightly bulging outward and the back cover is separating from the chassis. The phone still powers on and functions normally. Which of the following components is MOST likely causing this issue?
⚠ Common exam trap
CompTIA often tests the misconception that a functional phone means the battery is fine, but the question specifically describes physical deformation (bulging, separation) which is a battery symptom regardless of normal operation.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
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Battery
A bulging screen and separating back cover are classic signs of a swollen lithium-ion battery. As the battery degrades, internal chemical reactions produce gas, causing the battery casing to swell and physically push against the phone's chassis. This occurs even if the phone still powers on and functions normally, as the battery can still deliver voltage while its physical integrity is compromised.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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Battery
Why this is correct
A lithium-ion battery can swell when internal pressure builds up from gas generated by electrolyte decomposition or internal short-circuiting, which physically forces the screen and chassis apart and creates a bulge. This is a recognized safety hazard because the swelling indicates potential for rupture, leakage, or thermal runaway. A swollen battery is the definitive cause of case separation, not a software or input-layer fault.
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Digitizer
Why it's wrong here
The digitizer is a thin capacitive or resistive layer bonded to the glass that captures touch input; it does not contain materials that generate gas or expand, so its failure can only manifest as unresponsive or ghost touches. Since it lies flat and is applied directly under the display, any swelling in that layer would be on the micron scale and could not push the screen outward. Touch-layer faults are purely electromagnetic or conductive in nature, leaving the physical shell unaffected.
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LCD panel
Why it's wrong here
An LCD panel is a sandwich of liquid crystal, polarizers, and glass; a malfunction produces visual artifacts like lines, color shifts, or backlight bleed, but the panel itself is rigid and does not house electrochemistry that creates pressure. Unless the LCD is physically cracked from impact, it will not deform the device's outer contour. Separation of the case is a mechanical event caused by an internal force, which the passive glass LCD assembly cannot generate.
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Charging port
Why it's wrong here
The charging port is a small mechanical connector soldered to the logic board, and its failure modes involve intermittent connection, broken pins, or short circuits that affect power delivery. It has no enclosed volume or active chemistry to expand, so a damaged port would never produce a bulging appearance. Any swelling adjacent to the port is typically overlooked and is always a battery problem, not a port problem.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 220-1101 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 220-1101 exam.