CBSE Class 11 Informatics Practices Question Paper Set 10 with Solutions

Answer: A loop is a programming construct that repeats a block of statements again and again as long as a given condition is true (or for a fixed number of times), e.g. for and while loops in Python.

Teacher's Note:
1. A loop is Python's iteration structure.
2. Always mention that the block repeats while the condition holds.

Answer: The keyword not (a logical operator that reverses a Boolean value, e.g. not True gives False).

Teacher's Note:
1. Python uses words for logical operators: and, or, not.
2. Do not confuse it with the symbol ! which is used only in !=.

Answer: Code B is an augmented assignment: it adds 2 to the current value of Q and stores the result back in Q, i.e. Q = Q + 2. Q becomes 7.

Teacher's Note:
1. The operator += combines addition and assignment.
2. It changes Q itself, it is not a comparison.

Answer: There is no mistake. SQL keywords are not case sensitive, the condition is valid and the statement ends with a semicolon. Written conventionally: SELECT name FROM STU WHERE MARK > 90;

Teacher's Note:
1. Keywords written in lower case still work in MySQL.
2. Do not invent an error; check column names, keywords and the semicolon before deciding.

Answer: Flowchart. It uses standard symbols joined by arrows to show the flow of an algorithm.

Teacher's Note:
1. A flowchart is the picture form of an algorithm.
2. Pseudocode is the text form, so keep the two apart.

Answer: // is floor division. 56 ÷ 3 = 18.67, floor is 18. So C = 18.

Teacher's Note:
1. Floor division gives the integer part of the quotient, not a decimal.
2. The original code used an undefined name A; use the variable B that was assigned.

Answer: Any two of: ADD (add a column or constraint), MODIFY (change the data type of a column), DROP (remove a column), CHANGE (rename a column) / RENAME.

Teacher's Note:
1. ALTER changes the structure of a table, not its rows.
2. Use UPDATE, not ALTER, when you want to change data in rows.

Answer: A dictionary must be enclosed in curly braces { }, not round brackets (round brackets make a tuple, and key:value pairs are not allowed there).
Correct: D = {1:2, 3:4, 5:6}

Teacher's Note:
1. Dictionaries use curly braces with key:value pairs.
2. Keys must be unique and of an immutable type.

Answer: FALSE. A dictionary is mutable: items can be added, changed or deleted after creation. (Only its keys must be immutable.)

Teacher's Note:
1. Lists and dictionaries are mutable; strings and tuples are immutable.
2. Do not mix up immutable keys with an immutable dictionary.

Answer: DESC table_name; (or DESCRIBE table_name;), e.g. DESC EMP;

Teacher's Note:
1. It lists column names, data types, keys and defaults.
2. SHOW TABLES lists the tables, not the structure of one table.

Answer: list() converts a string into a list of its characters.
Output: ['H', 'E', 'L', 'L', 'O']

Teacher's Note:
1. list() on a string splits it into single characters.
2. The printed list shows quotes and commas, so write them.

Answer: The loop variable a takes each element in turn and prints it on a new line.
Output:

5
2
3
7
1

Teacher's Note:
1. Print the same variable that the for loop uses.
2. Each print() statement ends with a new line by default.

Answer: append() adds its argument as a single element at the end, so L2 becomes a nested list inside L1.
Output: [2, 3, 7, 1, [0, 9, 3]]

Teacher's Note:
1. append() adds one item; extend() would add the items separately.
2. L1 now has 5 elements, the last being a list.

Answer: Looping over a dictionary gives its keys in insertion order.

Mohan : 95
Ram : 89
Suhel : 92
Sangeeta : 85

Teacher's Note:
1. print() with commas puts a space between the values.
2. So the output is Mohan : 95, with a space on both sides of the colon.

Answer: Assigning to a new key adds a new key:value pair.
Output: {'Mohan': 95, 'Ram': 89, 'Suhel': 92, 'Sangeeta': 85, 'Meena': 78}

Teacher's Note:
1. Assigning to a missing key adds it; assigning to an existing key changes its value.
2. New items appear at the end.

Answer: update() adds all key:value pairs of D1 into D.
Output: {'M': 95, 'R': 89, 'S': 92, 'A': 25, 'K': 35}

Teacher's Note:
1. update() changes D itself and D1 stays the same.
2. If a key already existed in D, its value would be overwritten.

Answer: i) get('Ram') returns the value of key 'Ram': 89
ii) dict_keys(['Mohan', 'Ram', 'Suhel', 'Sangeeta', 'Meena'])
iii) dict_values([95, 89, 92, 85, 78])

Teacher's Note:
1. keys() and values() return view objects, so the output carries the dict_keys and dict_values wrapper.
2. get() returns None instead of an error when a key is missing.

Answer: i) SELECT * FROM EMP WHERE ADDRESS LIKE '%a';
(Result: 202, Samprada, Meghalaya, Ahim)
ii) SELECT NAME, Father FROM EMP WHERE EMP_CODE BETWEEN 202 AND 204;
(Result: Samprada-Ahim, Rahul-Rohit, Anushka-AAAA; BETWEEN includes both ends)
iii) DELETE FROM EMP WHERE NAME = 'Rahul';
(removes the row with EMP_CODE 203)

Teacher's Note:
1. % stands for any number of characters, so '%a' means ends with a.
2. Never write DELETE without WHERE, because it removes every row.

Answer: 1. Primary key: a column (or set of columns) whose values uniquely identify each row of a table. It cannot contain duplicate or NULL values, and a table can have only one primary key.
2. Create table:

CREATE TABLE EMP (
  EMP_CODE INT PRIMARY KEY,
  NAME VARCHAR(20),
  ADDRESS VARCHAR(30),
  Father VARCHAR(20)
);

INSERT INTO EMP VALUES (201, 'Nitish', 'Delhi', 'Rahul');

Teacher's Note:
1. Text values go in single quotes, numbers do not.
2. Inserting a second row with EMP_CODE 201 would give a duplicate-key error.

Answer: 1. It can contain letters (A-Z, a-z), digits (0-9) and the underscore (_) only.
2. It must start with a letter or an underscore, never with a digit.
3. It cannot contain spaces or special characters such as $, +, @, -.
4. It cannot be a Python keyword (e.g. if, for, while).
5. Names are case sensitive (marks and Marks are different) and should be meaningful, e.g. total_marks.

Teacher's Note:
1. Give an example of a valid and an invalid name to earn full marks.
2. Remember that 2num is invalid but num2 is valid.

Answer: INSERT INTO MARKET VALUES ('APS101', 'JCO', 'Jason', 'Rameshor', 50000, 1234567, 'Yes');
(The remaining rows are inserted in the same way, or in one statement with the row lists separated by commas.)

Teacher's Note:
1. The values must follow the column order of the table.
2. Put quotes around text values such as 'JCO' and 'Yes'.

Answer: ALTER TABLE MARKET MODIFY SALARY VARCHAR(20);

Teacher's Note:
1. MODIFY changes the data type of an existing column.
2. ADD is for new columns and DROP is for removing columns.

Answer: UPDATE MARKET SET CATEGORY = 'General' WHERE CATEGORY = 'Civil';

Teacher's Note:
1. UPDATE changes existing data and needs SET.
2. Without WHERE every row would be changed.

Answer: SELECT FATHER FROM MARKET WHERE STU_NAME LIKE '___x%';
(Each underscore stands for exactly one character. Result: Sunita, since 'Alexendir' has x as its fourth letter.)

Teacher's Note:
1. _ matches exactly one character, while % matches any number of characters.
2. Use three underscores before x to make it the fourth letter.

Answer: SELECT ADM_NO FROM MARKET WHERE CATEGORY = 'JCO' ORDER BY STU_NAME DESC;
(Result: APS101 (Rameshor), APS 111 (Anthony))

Teacher's Note:
1. WHERE comes before ORDER BY in a query.
2. ORDER BY is ascending by default, so write DESC for descending.

Answer: UPDATE MARKET SET SALARY = SALARY + SALARY * 0.10;
(equivalently SET SALARY = SALARY * 1.10). No WHERE clause is needed because all rows are to be changed.

Teacher's Note:
1. The new value can be calculated from the old value in the same statement.
2. Do not add a WHERE clause when the change is for every row.

Answer: BETWEEN includes both limits, so salaries 50000, 60000, 70000 and 80000 qualify.
Output: APS101, APS 105, APS 103, APS 102 (four rows).

Teacher's Note:
1. BETWEEN is inclusive of both end values.
2. List the rows in the same order as they are stored in the table.

Answer: The column VEHICLE is removed from the table along with all its data. The table now has six columns: ADM_NO, CATEGORY, FATHER, STU_NAME, SALARY, PHONE.

Teacher's Note:
1. ALTER with DROP deletes a whole column, not a row.
2. This change cannot be undone, so use it carefully.

Answer: The pattern needs names whose fifth letter is 'e' (four underscores, then e). These are Asween and Alexendir. So ADM_NO of these two rows (APS 105 and APS 104) becomes empty (blank); other rows are unchanged. MySQL reports 2 rows affected.

Teacher's Note:
1. Count the underscores to find the position of the letter.
2. Check each name letter by letter; Rameshor has e as its fourth letter, not the fifth.

Answer: Rows are sorted by salary from highest to lowest:
1. Teacher, Sunita (90000)
2. Staff, Kukrejha (80000)
3. Civil, Proloy Nath (70000)
4. ORs, Rishab Das (60000)
5. JCO, Jason (50000)
6. LDC, Sany (30000)
7. JCO, Ammy (25000)
8. MTS, Pintu (20000)

Teacher's Note:
1. Only the columns named in SELECT are shown, not SALARY.
2. The sorting is done by SALARY even though SALARY is not displayed.

Answer: (b) Ascending order. ORDER BY sorts in ascending order unless DESC is written.

Teacher's Note:
1. ASC is the default for ORDER BY.
2. Without ORDER BY, rows appear in no guaranteed order.

Answer: (c) WHERE. It filters rows according to a condition (HAVING filters groups, AS gives an alias).

Teacher's Note:
1. WHERE is the basic filter clause of a SELECT query.
2. AS only renames a column or table in the output.

Answer: (d) PQ. The others contain a space or a special character, which is not allowed in identifiers.

Teacher's Note:
1. Only letters, digits and underscore are allowed in names.
2. A space splits a name into two tokens.

Answer: (a) UNIQUE. It rejects a repeated value in the column. (DISTINCT is used in SELECT, not as a constraint.)

Teacher's Note:
1. Constraints are rules placed on columns when a table is created.
2. UNIQUE allows NULL, while PRIMARY KEY does not.

Answer: (c) UPDATE. It modifies the existing data in rows; ALTER TABLE changes the structure.

Teacher's Note:
1. UPDATE works on data and ALTER works on structure.
2. REPLACE TABLE and CHANGE TABLE are not valid commands.

Answer: Data Manipulation Language. It includes INSERT, UPDATE, DELETE and SELECT commands.

Teacher's Note:
1. DML works on the data stored in tables.
2. DDL (CREATE, ALTER, DROP) works on the structure.

Answer: (b) False. Keywords are reserved words with a fixed meaning and cannot be used as variable names.

Teacher's Note:
1. Words like if, for and while are reserved.
2. You can see all keywords using the keyword module.

Answer: (c) a and not b. The words and and not are logical operators. (a) is arithmetic, (b) is relational and (d) is a membership operator.

Teacher's Note:
1. The logical operators are and, or and not.
2. The original option (c) was not a valid expression, so it is corrected.

Answer: False. len() returns the number of items (key:value pairs) in a dictionary; values are input using input() or assigned directly.

Teacher's Note:
1. len() counts items and does not read input.
2. For a dictionary, len() gives the number of keys.

Answer: (a) data types. Type casting converts a value from one data type to another, e.g. int('5') or float(3).

Teacher's Note:
1. Type conversion functions are int(), float(), str() and list().
2. Conversion done by Python itself is implicit, and by the programmer is explicit.

Answer: (c) a is equal to 5. The operator == compares values and gives True or False; it does not assign.

Teacher's Note:
1. A single = assigns and a double == compares.
2. Writing = instead of == in a condition is a common error.

Answer: (d) L1 != L2. L2 has a nested list as its second element, so the lists are not equal and L1 != L2 gives True. (<> is not valid in Python 3.)

Teacher's Note:
1. Lists are equal only if all elements match in order.
2. The operator <> existed in Python 2 only.

Answer: (a) True. Lists are compared element by element: 1 = 1, 2 = 2, then 3 < 5, so L1 < L2 is True.

Teacher's Note:
1. Comparison stops at the first position where the elements differ.
2. The length of the list matters only when one list is a prefix of the other.

Answer:

L1 = [1, 2, 3, 4]
L2 = [10, 20, 30, 40]

# (a) add the elements of the two lists
result = []
for i in range(len(L1)):
    result.append(L1[i] + L2[i])
print("Sum list:", result)

# (b) delete an element
x = int(input("Enter the element to delete: "))
if x in result:
    result.remove(x)
else:
    print("Element not found")
print("List now:", result)

Teacher's Note:
1. Use range(len(list)) to go through both lists by position.
2. Check with in before remove(), because remove() gives an error if the value is missing.

Answer:

D = {'Mohan': 95, 'Ram': 89, 'Suhel': 92}

# (a) remove a key using pop()
k = input("Enter key to remove: ")
v = D.pop(k, None)
if v is None:
    print("Key not found")
else:
    print("Removed", k, ":", v)
print("Dictionary:", D)

# (b) clear all elements
D.clear()
print("After clear:", D)

Teacher's Note:
1. pop(key) removes that key and returns its value.
2. clear() empties the dictionary but the dictionary itself still exists.

Answer:

n = int(input("How many elements? "))
L = []
for i in range(n):
    L.append(int(input("Enter element: ")))
key = int(input("Enter element to search: "))

found = False
for i in range(len(L)):
    if L[i] == key:
        print("Element found at position", i + 1)
        found = True
        break
if not found:
    print("Element not found")

Teacher's Note:
1. Linear search checks the elements one by one from the start.
2. Use a flag variable or a for-else so that the not-found message is printed only once.

Answer:

n = int(input("How many elements? "))
L = []
for i in range(n):
    L.append(int(input("Enter element: ")))

L.sort()                 # ascending order
print("Sorted list:", L)
print("Largest element:", L[-1])

Teacher's Note:
1. After an ascending sort, the largest item is the last item, L[-1].
2. sort() changes the original list and returns None, so do not write L = L.sort().