19 Operating Systems (Computer Science) questions asked in BEL PE previous year papers, each with the correct answer and explanation. Read them free on UTpaper, or attempt the full papers as timed online tests.
During the design and analysis process of an algorithm to find the kth smallest element in an unsorted array, a researcher proposes using a modified divide-and-conquer approach that always divides the array into five nearly equal parts, recursively selects the median of each part, and then finds the median of those medians to use as a pivot for partitioning.
Which of the following best describes the time complexity and design implication of this algorithm?
AO(n); because the median-of-medians approach ensures balanced partitions and linear-time selection.
BO(n log n); because the algorithm behaves like mergesort.
CO(log n); because the recursion depth reduces logarithmically.
DO(n²); because repeated partitioning leads to quadratic comparisons.
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Correct answer: (A) O(n); because the median-of-medians approach ensures balanced partitions and linear-time selection.
A system uses variable partition memory management with the following free memory blocks (in KB):
Block 1: 100, Block 2: 500, Block 3: 200, Block 4: 300, Block 5: 600
Four processes arrive in the following order with their memory requirements (in KB):
P1: 212, P2: 417, P3: 112, P4: 426
Using the Best Fit allocation strategy, determine which block each process is allocated to and how much total internal fragmentation remains at the end of all allocations.
A system uses fixed partitioning with the following memory blocks and process allocations:
Block Size (MB) – Process Size (MB)
4 – 1
8 – 7
8 – 7
16 – 14
Which statement is true about internal and external fragmentation?
In an FCFS-scheduled system, five processes arrive at time 0:
P1 (CPU-bound, 20 ms) and P2–P5 (I/O-bound, 2–5 ms).
Which outcome is most likely under FCFS?
ACPU utilization improves because short processes preempt the long one.
BAverage waiting time becomes minimal for all processes.
CContext switching increases as I/O-bound processes repeatedly interrupt P1.
DI/O-bound processes face starvation due to the convoy effect caused by P1.
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Correct answer: (D) I/O-bound processes face starvation due to the convoy effect caused by P1.
A data scientist is developing a predictive model for loan default detection using a dataset that contains labelled examples of previous loan applications marked as 'defaulted' or 'not defaulted'. However, during model training, the algorithm shows very high accuracy on training data but performs poorly on new unseen test data. Despite adding more labelled data, the issue persists. Which of the following best explains the underlying problem in the supervised learning process?
AThe model suffers from overfitting due to poor generalisation.
BThe dataset lacks sufficient labelling for supervised learning.
CThe model applies an unsupervised clustering technique instead of classification.
DThe algorithm fails due to lack of a defined loss function.
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Correct answer: (A) The model suffers from overfitting due to poor generalisation.
In a multimedia operating system, which of the following functionalities is most critical to ensure continuous playback of audio and video streams without jitter or frame drops?
AFile system encryption and access control
BSupport for multiple user logins with access control
CReal-time process scheduling with deadline constraints
DBatch processing for background tasks
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Correct answer: (C) Real-time process scheduling with deadline constraints
Which of the following is NOT the necessary condition for the deadlock?
ACircular wait
BPreemption
CHold and wait
DMutual exclusion
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Correct answer: (B) Preemption
How to use these BEL PE Computer Science questions
Every question here was asked in a real BEL PE paper; the paper and shift are shown on the card, and the number opens the question on its own page. Try each one before tapping Show answer, then attempt the full BEL PE papers as timed tests to check your speed under exam conditions.