Cyber Sleuth Tier 1

What will be the output of the following code?

• [1, 2]

• [2,3]

• [3,4]

• [3,4,5]

Answer explanation

The slicing a[2:4] returns elements from index 2 up to (but not including) index 4.

Which of the following is the correct way to open a file for reading in Python?

• file = open('filename.txt', 'w')

• file = open('filename.txt', 'r')

• file = open('filename.txt', 'a')

• file = open('filename.txt', 'x')

Answer explanation

The mode 'r' opens the file for reading.

Given the dictionary

d = {'one': 1, 'two': 2, 'three': 3},

what is the result of d.get('four')?

• None

• KeyError

• 0

• 4

Answer explanation

The get() method returns None if the key is not found and no default value is provided.

What will be the output of the following code?

• a: 1 b: 5 c: 10

• a: 1 b: 2 c: 10

• a: 1 b: 2 c: 5

• a: 1 b: 5 c: 2

Answer explanation

The function call func(1, 2) assigns 1 to a and 2 to b, using the default value 10 for c.

What is the output of the following code snippet?

• [1, 2, 3]

• [1, 2, 3, 4]

• [2]

• None

Answer explanation

b is a reference to a, so changes to b affect a

Which of the following is a mutable data type in Python?

• int

• str

• tuple

• list

Answer explanation

Lists are mutable, meaning their elements can be changed.

How do you create a set in Python?

• s = {}

• s = set([])

• s = []

• s = ()

Answer explanation

set([]) creates an empty set. {} creates an empty dictionary.

What will be the output of the following code?

• {1, 2, 3, 4, 5}

• {3}

• {1, 2, 3}

• {}

Answer explanation

The & operator returns the intersection of sets a and b.

How can you create a new list that contains the squares of all elements in the original list

a = [1, 2, 3, 4]?

• [x**2 for x in a]

• [x^2 for x in a]

• [a**2]

• [x*x for x in a]

Answer explanation

List comprehension [x**2 for x in a] creates a new list with squares of all elements in a.

What will be the output of the following code?

print("Hello {name}".format(name="Alice"))

• Hello name

• Hello {name}

• Hello Alice

• Hello

Answer explanation

The format method replaces {name} with the provided value "Alice".