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GK One-Line Question & Answer

15541+ short questions with short answers, covering every category and sub-category on the site — no long articles to scroll through. Good for a fast recap before an exam, or a few minutes of daily practice.

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Computer Fundamentals → Introduction to Computer 39

Which isolation level prevents dirty reads, phantom reads, and non-repeatable reads?
Serializable
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Dirty read in databases occurs when?
Transaction reads uncommitted data from another transaction
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Phantom read occurs when?
Same query returns different rows in same transaction due to another transaction's INSERT/DELETE
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Database sharding is?
Horizontal partitioning of data across multiple database instances
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Read replica in databases is used for?
Scaling read operations — copy of primary database for SELECT queries
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Connection pooling in applications?
Reuses existing database connections from a pool — improves performance
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ORM (Object Relational Mapping) maps?
Object-oriented code classes to database tables automatically
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Which NoSQL type stores data as key-value pairs?
Key-value store
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Which data type in Python is immutable?
Tuple
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Python list comprehension [x*2 for x in range(5)] produces?
[0,2,4,6,8]
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What does len([1,2,3,4,5]) return in Python?
5
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Python dictionary key must be?
Immutable (string, int, tuple)
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Which Python keyword is used to handle exceptions?
except
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What is the output of print(type(3.14)) in Python?
<class 'float'>
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Python's 'pass' statement?
Does nothing — placeholder for empty code block
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Which Python function converts integer to string?
str()
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Python range(1,10,2) generates?
[1,3,5,7,9]
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Lambda in Python is?
An anonymous function defined in one line
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What does *args in Python function mean?
Variable number of positional arguments as tuple
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**kwargs in Python?
Variable number of keyword arguments as dictionary
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Python decorator is used to?
Wrap a function to modify or extend its behavior without changing its code
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Generator in Python uses which keyword?
yield
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Python 'with' statement is used for?
Context management — automatically handles resource cleanup (close files)
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What does __init__ method do in Python class?
Constructor — initializes a new object instance's attributes
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Inheritance in Python is defined as?
class Child(Parent):
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Python multiple inheritance is?
Supported — class C(A, B): inherits from both A and B
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MRO (Method Resolution Order) in Python?
Order in which Python searches classes for method/attribute in inheritance
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Python __str__ method is called by?
print() function and str() conversion
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What is the output of 5//2 in Python?
2
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Python operator ** is used for?
Exponentiation (power)
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Which Python module is used for regular expressions?
re
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os.path.join() in Python is used for?
Building file paths in an OS-independent way
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Which Python library is used for HTTP requests?
requests
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JSON module in Python provides?
Encoding/decoding JSON data (json.dumps, json.loads)
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Python f-strings (f'Hello {name}') provide?
Inline expression evaluation within strings (formatted string literals)
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Which Python keyword checks membership in a sequence?
in
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enumerate() in Python?
Returns index-value pairs when iterating over a sequence
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What is the output of bool('') in Python?
False
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Python None is?
Null equivalent — absence of value
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Computer Fundamentals → Software and Hardware 1

Python's GIL (Global Interpreter Lock) affects?
Multi-threading — prevents true parallel execution of Python threads in CPython
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