NCERT Solutions Class 11 Computer Science Chapter 5 2026-27

Expert view: Read the NCERT keyword in the stem first, then test the Python rule in a small dry run.

1. Serial_no. is invalid because it contains a full stop.
2. 1st_Room is invalid because an identifier cannot start with a digit.
3. Hundred$ is invalid because dollar sign is not allowed.
4. Total Marks is invalid because spaces are not allowed.
5. total-Marks is invalid because hyphen is read as a minus operator.
6. True is invalid because it is a Python keyword and Boolean literal.

Valid: Total_Marks
Valid: _Percentage
Invalid: Serial_no.
Invalid: 1st_Room
Invalid: Hundred$
Invalid: Total Marks
Invalid: total-Marks
Invalid: True

Answer: Invalid identifiers are Serial_no., 1st_Room, Hundred, Total Marks, total-Marks and True. Total_Marks and _Percentage are valid.

Expert view: Read the NCERT keyword in the stem first, then test the Python rule in a small dry run.

1. Assign numeric values directly without quotation marks.
2. Use a list to store the stationery strings.
3. Store each part of the name as a separate string.
4. Concatenate the three strings with blank spaces between them.

length = 10
breadth = 20
sum = (length + breadth) / 2
stationery = ['Paper', 'Gel Pen', 'Eraser']
first = 'Mohandas'
middle = 'Karamchand'
last = 'Gandhi'
fullname = first + ' ' + middle + ' ' + last

Answer: length = 10, breadth = 20, sum = (length + breadth) / 2, stationery = ['Paper', 'Gel Pen', 'Eraser'], first = 'Mohandas', middle = 'Karamchand', last = 'Gandhi', fullname = first + ' ' + middle + ' ' + last.

Expert view: Read the NCERT keyword in the stem first, then test the Python rule in a small dry run.

1. The sum of 20 and -10 is 10, and 10 is less than 12.
2. Not more than 24 means less than or equal to 24.
3. Between two numbers can be written as a chained comparison.
4. String order can be tested with comparison operators.
5. An empty list can be checked by comparing it with an empty list.

(20 + -10) < 12
num3 <= 24
num1 < 6.75 < num2
first < middle < last
Stationery == []

Answer: (20 + -10) < 12 gives True; num3 <= 24; num1 < 6.75 < num2; first < middle < last; Stationery == [].

Expert view: Read the NCERT keyword in the stem first, then test the Python rule in a small dry run.

1. Use 1 == 2 to produce False, then compare 0 with False.
2. Use 3 == 4 to produce False, which behaves as 0 in arithmetic.
3. Compare two false comparisons with each other for the third expression.

0 == (1 == 2)
2 + (3 == 4) + 5 == 7
(1 < -1) == (3 > 4)

Answer: 0 == (1 == 2); 2 + (3 == 4) + 5 == 7; (1 < -1) == (3 > 4).

Expert view: Read the NCERT keyword in the stem first, then test the Python rule in a small dry run.

1. In part a, num2 is assigned 5 before num1 is changed to 2.
2. In part b, tuple assignment swaps using the old right-side values.
3. In part c, num3 is used before it has any assigned value in the snippet.

# a output
2 5
# b output
6 4
# c
NameError: name 'num3' is not defined

Answer: Part a prints 2 5. Part b prints 6 4. Part c gives NameError because num3 is used before assignment.

Expert view: Read the NCERT keyword in the stem first, then test the Python rule in a small dry run.

1. A count such as number of months is an integer.
2. A yes or no value is Boolean.
3. A mobile number is best stored as a string because it is an identifier, not a quantity for arithmetic.
4. Money, volume and perimeter may need decimal values.
5. Name and address are text values, so they use string.

months = 12              # int
residentDelhi = True     # bool
mobile = '9876543210'    # str
pocketMoney = 150.50     # float
volume = 1436.76         # float
perimeter = 20.0         # float
name = 'Asha'            # str
address = 'Delhi'        # str

Answer: int, bool, str, float, float, float, str and str respectively.

Expert view: Read the NCERT keyword in the stem first, then test the Python rule in a small dry run.

1. num1 += num2 + num3 makes num1 equal to 9.
2. 4 ** (3 + 2) is 4 ** 5, which is 1024.
3. '5' + '5' joins strings and gives '55'.
4. int('3.14') raises ValueError because the string is not an integer literal.
5. The remaining Boolean expressions evaluate after arithmetic and comparison precedence.

a) 9
b) 1024
c) num1 becomes 1024
d) 55
e) 1.0
f) 27.2
g) 3
h) 10.0
i) ValueError
j) False
k) True
l) True
m) True
n) True

Answer: Outputs are 9, 1024, 1024, 55, 1.0, 27.2, 3, 10.0, ValueError, False, True, True, True and True.

Expert view: Read the NCERT keyword in the stem first, then test the Python rule in a small dry run.

1. Both statements use valid Python syntax.
2. Both attempt division by zero.
3. Division by zero is detected only when the line executes.

25 / 0                  # runtime error
num1 = 25; num2 = 0
num1 / num2             # runtime error

Answer: Both are runtime errors. Python raises ZeroDivisionError.

Expert view: Read the NCERT keyword in the stem first, then test the Python rule in a small dry run.

1. The center is (0, 0), so distance squared is x*x + y*y.
2. The radius is 10, so radius squared is 100.
3. Use x*x + y*y <= 100 as the Boolean expression.
4. Substitute each given coordinate and compare with 100.

x*x + y*y <= 100
(0, 0)   -> True
(10,10)  -> False
(6, 6)   -> True
(7, 8)   -> False

Answer: Expression: x*x + y*y <= 100. Results: (0,0) True, (10,10) False, (6,6) True, (7,8) False.

Expert view: Read the NCERT keyword in the stem first, then test the Python rule in a small dry run.

1. Read or assign the Celsius value.
2. Apply fahrenheit = celsius * 9 / 5 + 32.
3. For 100 degree Celsius, the result is 212 degree Fahrenheit.
4. For 0 degree Celsius, the result is 32 degree Fahrenheit.

celsius = float(input('Enter Celsius: '))
fahrenheit = celsius * 9 / 5 + 32
print(fahrenheit)
print('Boiling:', 100 * 9 / 5 + 32)
print('Freezing:', 0 * 9 / 5 + 32)

Answer: Boiling point is 212 degree Fahrenheit and freezing point is 32 degree Fahrenheit.

Expert view: Read the NCERT keyword in the stem first, then test the Python rule in a small dry run.

1. Read principal P, rate R and time T.
2. Compute SI = P * R * T / 100.
3. Compute amount = P + SI.
4. Print both simple interest and amount payable.

P = float(input('Principal: '))
R = float(input('Rate: '))
T = float(input('Time: '))
SI = P * R * T / 100
amount = P + SI
print(SI)
print(amount)

Answer: SI = (P * R * T) / 100 and amount payable = P + SI.

Expert view: Read the NCERT keyword in the stem first, then test the Python rule in a small dry run.

1. Read x, y and z, the days taken by A, B and C alone.
2. Compute numerator = x * y * z.
3. Compute denominator = x*y + y*z + x*z.
4. Divide numerator by denominator to get combined days.

x = float(input('Days by A: '))
y = float(input('Days by B: '))
z = float(input('Days by C: '))
days = x * y * z / (x * y + y * z + x * z)
print(days)

Answer: days = x*y*z / (x*y + y*z + x*z).

Expert view: Read the NCERT keyword in the stem first, then test the Python rule in a small dry run.

1. Read two integers.
2. Apply each arithmetic operator to the pair.
3. Print a clear label with each result.
4. Avoid division by zero in real use by checking the second number.

a = int(input('First integer: '))
b = int(input('Second integer: '))
print('Sum', a + b)
print('Difference', a - b)
print('Product', a * b)
print('Quotient', a / b)
print('Floor quotient', a // b)
print('Remainder', a % b)
print('Power', a ** b)

Answer: The program prints sum, difference, product, quotient, floor quotient, remainder and power.

Expert view: Read the NCERT keyword in the stem first, then test the Python rule in a small dry run.

1. Read the two numbers.
2. Store the first number in temp.
3. Assign the second number to the first variable.
4. Assign temp to the second variable.

a = int(input('First number: '))
b = int(input('Second number: '))
temp = a
a = b
b = temp
print(a, b)

Answer: Use temp = a, a = b, b = temp.

Expert view: Read the NCERT keyword in the stem first, then test the Python rule in a small dry run.

1. Read the two numbers.
2. Write a, b = b, a.
3. Python evaluates the right side first.
4. It then assigns the values to the left side names.

a = int(input('First number: '))
b = int(input('Second number: '))
a, b = b, a
print(a, b)

Answer: Use a, b = b, a.

Expert view: Read the NCERT keyword in the stem first, then test the Python rule in a small dry run.

1. Read integer n.
2. Use a loop if each message should appear on a new line.
3. In each iteration, print GOOD MORNING.
4. Repeat until the loop has run n times.

n = int(input('Enter n: '))
for i in range(n):
    print('GOOD MORNING')

Answer: Use for i in range(n): print('GOOD MORNING').

Expert view: Read the NCERT keyword in the stem first, then test the Python rule in a small dry run.

1. Read the three numbers.
2. Add them.
3. Divide the sum by 3.
4. Print the average.

a = float(input('First: '))
b = float(input('Second: '))
c = float(input('Third: '))
average = (a + b + c) / 3
print(average)

Answer: average = (a + b + c) / 3.

Expert view: Read the NCERT keyword in the stem first, then test the Python rule in a small dry run.

1. Import math to use the value of pi.
2. Store the radii in a list.
3. For each radius, compute volume = 4/3 * pi * r**3.
4. Print the radius and the corresponding volume.

import math
for r in [7, 12, 16]:
    volume = 4 / 3 * math.pi * r ** 3
    print(r, volume)

Answer: Approximate volumes are 1436.76 cubic cm, 7238.23 cubic cm and 17157.28 cubic cm.

Expert view: Read the NCERT keyword in the stem first, then test the Python rule in a small dry run.

1. Read the user's name and age.
2. Find remaining years as 100 - age.
3. Add remaining years to the current year.
4. Print a message using the user's name.

from datetime import date
name = input('Enter name: ')
age = int(input('Enter age: '))
current_year = date.today().year
year100 = current_year + (100 - age)
print(name, 'will turn 100 in', year100)

Answer: year100 = current_year + (100 - age).

Expert view: Read the NCERT keyword in the stem first, then test the Python rule in a small dry run.

1. Read mass m.
2. Store speed of light as c = 3 * 10**8.
3. Compute E = m * c**2.
4. Print the energy.

m = float(input('Mass in kg: '))
c = 3 * 10 ** 8
E = m * c ** 2
print(E)

Answer: E = m * (3 * 10**8) ** 2.

Expert view: Read the NCERT keyword in the stem first, then test the Python rule in a small dry run.

1. Import math for sine and radians.
2. Convert each angle from degrees to radians.
3. Compute height = length * sin(angle).
4. For the four cases, round the result to two decimal places.

import math
pairs = [(16, 75), (20, 0), (24, 45), (24, 80)]
for length, angle in pairs:
    height = length * math.sin(math.radians(angle))
    print(round(height, 2))

Answer: Approximate heights are 15.45 ft, 0.00 ft, 16.97 ft and 23.64 ft.

Expert view: Read the NCERT keyword in the stem first, then test the Python rule in a small dry run.

1. Choose fields such as admission number, name, class, section, roll number, date of birth, blood group and contact number.
2. Accept each field using input.
3. Store every field in a clearly named variable.
4. Print the details under labels so the record is readable.

adm_no = input('Admission number: ')
name = input('Name: ')
class_name = input('Class: ')
section = input('Section: ')
roll_no = input('Roll number: ')
dob = input('Date of birth: ')
blood_group = input('Blood group: ')
contact = input('Contact number: ')
print('Student Identity Details')
print('Admission No:', adm_no)
print('Name:', name)
print('Class:', class_name, section)
print('Roll No:', roll_no)
print('DOB:', dob)
print('Blood Group:', blood_group)
print('Contact:', contact)

Answer: Accept student identity-card fields and display them with labels such as Name, Class, Section, Roll Number and Contact.