Q.131
Medium
Which of the following is a correct SQL syntax for creating an index on multiple columns?
A
CREATE INDEX idx_name ON table_name (col1, col2);
B
CREATE UNIQUE INDEX idx_name ON table_name (col1, col2);
C
CREATE INDEX idx_name ON table_name COLUMNS (col1, col2);
D
Both A and B are correct
Correct Answer:
D. Both A and B are correct
Explanation:
Both syntaxes are valid in SQL. The first creates a composite index, while the second creates a unique composite index.
Q.132
Medium
Which sorting algorithm has the best average-case time complexity for randomly distributed data?
A
Bubble Sort - O(n²)
B
Quick Sort - O(n log n)
C
Insertion Sort - O(n²)
D
Selection Sort - O(n²)
Correct Answer:
B. Quick Sort - O(n log n)
Explanation:
Quick Sort has O(n log n) average-case complexity, making it most efficient for random data. Though worst-case is O(n²), randomized pivot selection minimizes this risk.
Q.133
Medium
What does ACID compliance in databases ensure?
A
Data is always encrypted
B
Atomicity, Consistency, Isolation, and Durability of transactions
C
Automatic data compression
D
Asynchronous data backup
Correct Answer:
B. Atomicity, Consistency, Isolation, and Durability of transactions
Explanation:
ACID is a fundamental database property: Atomicity (all-or-nothing), Consistency (valid state), Isolation (concurrent independence), Durability (permanent after commit).
Q.134
Medium
Which cloud service model provides pre-configured application environments?
A
IaaS (Infrastructure as a Service)
B
PaaS (Platform as a Service)
C
SaaS (Software as a Service)
D
DaaS (Database as a Service)
Correct Answer:
B. PaaS (Platform as a Service)
Explanation:
PaaS provides a complete development and deployment environment in the cloud, including pre-configured tools and frameworks.
Q.135
Medium
Which of the following best describes a graph data structure with no cycles?
A
Directed Graph
B
Tree
C
Complete Graph
D
Bipartite Graph
Explanation:
A tree is a special case of a graph with no cycles. It has n nodes and n-1 edges, forming a hierarchical structure.
Q.136
Medium
In machine learning, what does overfitting mean?
A
The model is too simple to learn patterns
B
The model learns training data too well, including noise, reducing generalization to new data
C
The model has too many layers
D
The model requires more training data
Correct Answer:
B. The model learns training data too well, including noise, reducing generalization to new data
Explanation:
Overfitting occurs when a model learns the training data including its noise and irregularities, performing poorly on unseen test data.
Q.137
Medium
What is the primary advantage of using MongoDB (NoSQL) over traditional relational databases?
A
It provides ACID compliance on all operations
B
It has flexible schema that accommodates unstructured data and horizontal scalability
C
It uses SQL for all queries
D
It requires less storage space
Correct Answer:
B. It has flexible schema that accommodates unstructured data and horizontal scalability
Explanation:
MongoDB's document-based model allows flexible schemas for unstructured data and supports horizontal scaling, unlike rigid relational schemas.
Q.138
Medium
In operating systems, what is a deadlock?
A
When a process terminates unexpectedly
B
When two or more processes are blocked, each waiting for resources held by the other
C
When memory is exhausted
D
When the CPU stops functioning
Correct Answer:
B. When two or more processes are blocked, each waiting for resources held by the other
Explanation:
Deadlock is a situation where multiple processes cannot proceed because each holds resources needed by others, creating a circular wait condition.
Q.139
Medium
What is the correct order of operations for the Big O notation from least to most complex?
A
O(1) < O(n) < O(n²) < O(2ⁿ) < O(n!)
B
O(n!) < O(2ⁿ) < O(n²) < O(n) < O(1)
C
O(n) < O(1) < O(n²) < O(2ⁿ) < O(n!)
D
O(log n) > O(1) > O(n) > O(n²)
Correct Answer:
A. O(1) < O(n) < O(n²) < O(2ⁿ) < O(n!)
Explanation:
Constant O(1) is fastest, followed by logarithmic O(log n), linear O(n), quadratic O(n²), exponential O(2ⁿ), and factorial O(n!) which is slowest.
Q.140
Medium
Which normalization form eliminates all non-key dependencies?
Explanation:
3NF (Third Normal Form) ensures all non-key attributes depend only on the primary key, eliminating transitive dependencies.
