1. What is Scala primarily used for?
a) Web development
b) Data analysis
c) Both a and b
d) None of the above
Answer: c) Both a and b
2. What is the primary use of the "yield" keyword in a for-comprehension in Scala?
a) To filter elements.
b) To create a new collection.
c) To terminate the loop.
d) To define a new variable.
Answer: b) To create a new collection.
3. Which of the following is NOT a feature of Scala?
a) Immutable collections
b) Pattern matching
c) Checked exceptions
d) Type inference
Answer: c) Checked exceptions
4. Which of the following is NOT a valid collection type in Scala's standard library?
a) List
b) Tuple
c) Set
d) Queue
Answer: b) Tuple
5. What is the significance of "val" in Scala?
a) It defines a mutable variable.
b) It defines an immutable variable.
c) It is used to declare classes.
d) It is a loop control statement.
Answer: b) It defines an immutable variable.
6. What is the purpose of the "apply" method in Scala companion objects?
a) It is a constructor.
b) It is used to define type parameters.
c) It is a factory method.
d) It is used to implement pattern matching.
Answer: c) It is a factory method.
7. Which of the following is true about Scala's type system?
a) It only supports static typing.
b) It supports both static and dynamic typing.
c) It only supports dynamic typing.
d) It does not support typing at all.
Answer: b) It supports both static and dynamic typing.
8. Which keyword is used to create an anonymous function (lambda) in Scala?
a) fun
b) lambda
c) def
d) => (arrow symbol)
Answer: d) => (arrow symbol)
9. What is the difference between "var" and "val" in Scala?
a) "var" is immutable, while "val" is mutable.
b) "var" is used for variables, while "val" is used for values.
c) "var" is mutable, while "val" is immutable.
d) "var" and "val" are interchangeable.
Answer: c) "var" is mutable, while "val" is immutable.
10. What is the keyword used for defining a package in Scala?
a) package
b) import
c) module
d) namespace
Answer: a) package
11. Which keyword is used to define a class in Scala?
a) class
b) def
c) object
d) case
Answer: a) class
12. Which of the following is an example of a higher-order function in Scala?
a) map
b) val
c) if-else
d) while
Answer: a) map
13. What is the purpose of the "match" expression in Scala?
a) It defines a new variable.
b) It is used for looping.
c) It is used for pattern matching.
d) It is a keyword for type casting.
Answer: c) It is used for pattern matching.
14. In Scala, what is the role of the "extends" keyword when defining a class?
a) It defines the constructor.
b) It extends the class hierarchy.
c) It creates a new instance.
d) It is used for pattern matching.
Answer: b) It extends the class hierarchy.
15. In Scala, what is an "Option" used for?
a) To represent an optional value that can be either present or absent.
b) To define custom exceptions.
c) To declare variables with multiple values.
d) To define type aliases.
Answer: a) To represent an optional value that can be either present or absent.
16. Which collection type in Scala enforces unique elements?
a) List
b) Set
c) Array
d) Vector
Answer: b) Set
17. Which data structure in Scala is used for implementing a stack?
a) List
b) Array
c) Queue
d) Stack
Answer: a) List
18. What is the purpose of the "implicit" keyword in Scala?
a) It is used for type casting.
b) It declares a variable with inferred types.
c) It is used for implicit conversions and parameters.
d) It defines a class.
Answer: c) It is used for implicit conversions and parameters.
19. What is the purpose of the "yield" keyword in a for-comprehension in Scala?
a) To terminate the loop.
b) To transform the elements of a collection.
c) To define a new variable.
d) To declare a function.
Answer: b) To transform the elements of a collection.
20. Which of the following is a valid way to define a function in Scala?
a) function myFunction() {}
b) def myFunction: Unit = {}
c) method myFunction() {}
d) def myFunction() {}
Answer: d) def myFunction() {}
21. Which method is used to concatenate two strings in Scala?
a) concat
b) join
c) merge
d) +
Answer: d) +
22. What is the role of the "sealed" keyword when applied to a class or trait in Scala?
a) It prevents inheritance.
b) It allows inheritance from any other class.
c) It makes the class or trait public.
d) It is used for pattern matching.
Answer: a) It prevents inheritance.
23. What is the role of the "reduce" method in Scala?
a) It reduces the length of a collection.
b) It reduces the number of elements in a collection.
c) It combines the elements of a collection using a binary operation.
d) It removes duplicates from a collection.
Answer: c) It combines the elements of a collection using a binary operation.
24. Which operator is used for pattern matching in Scala?
a) ==
b) =
c) =>
d) ::
Answer: c) =>
25. What is the role of the "flatten" method in Scala?
a) It transforms a collection of collections into a single-level collection.
b) It sorts a collection in descending order.
c) It reverses the elements of a collection.
d) It removes duplicate elements from a collection.
Answer: a) It transforms a collection of collections into a single-level collection
26. Which collection type in Scala is both mutable and indexed?
a) List
b) Map
c) Array
d) Set
Answer: c) Array
27. What is the purpose of the "partition" method in Scala?
a) It divides a collection into two parts based on a predicate.
b) It sorts a collection in ascending order.
c) It reverses the elements of a collection.
d) It removes duplicate elements from a collection.
Answer: a) It divides a collection into two parts based on a predicate.
28. In Scala, what is the purpose of the "yield" keyword in a "for" loop?
a) To define a new variable.
b) To terminate the loop.
c) To return a value for each iteration.
d) To define a loop condition.
Answer: c) To return a value for each iteration.
29. What is the role of the "zip" method in Scala?
a) It combines two collections into a single collection of tuples.
b) It creates a zip file.
c) It filters a collection based on a predicate.
d) It reverses the elements of a collection.
Answer: a) It combines two collections into a single collection of tuples.
30. What is the role of the "throw" keyword in Scala?
a) It defines a new exception type.
b) It raises an exception.
c) It catches an exception.
d) It defines a loop condition.
Answer: b) It raises an exception.
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