CBSE Class 12 Informatics Practices · MCQ practice
CBSE Class 12 Informatics Practices Multiple Choice Questions, with Answers
8 practice questions for CBSE Class 12 Informatics Practices. Every question whose answer is the output of a program was run before publishing, so the answer is what the code really prints — not what it looks like it should.
1. What does this print?
import pandas as pd s = pd.Series([10, 20, 30]) print(s[1] + s[2])
- 30
- 40
- 50
- Error
Show the answer
Answer: 50
The default index starts at 0, so s[1] is 20 and s[2] is 30.
The default index starts at 0, so s[1] is 20 and s[2] is 30.
2. What is the output?
import pandas as pd
df = pd.DataFrame({'A': [1, 2], 'B': [3, 4]})
print(df.shape)- (2, 2)
- (2,)
- (4,)
- (2, 1)
Show the answer
Answer: (2, 2)
shape returns (rows, columns): two rows and two columns.
shape returns (rows, columns): two rows and two columns.
3. What does this print?
import pandas as pd
df = pd.DataFrame({'M': [10, 20, 30, 40]})
print(df['M'].mean())- 20.0
- 25.0
- 30.0
- 100
Show the answer
Answer: 25.0
The mean of 10, 20, 30 and 40 is 100 divided by 4.
The mean of 10, 20, 30 and 40 is 100 divided by 4.
4. Which selects rows by LABEL rather than position?
- iloc
- loc
- head
- at_position
Show the answer
Answer: loc
loc works on labels; iloc works on integer positions.
loc works on labels; iloc works on integer positions.
5. Which aggregate function ignores NULL values?
- COUNT(*)
- COUNT(column)
- both
- neither
Show the answer
Answer: COUNT(column)
COUNT(*) counts every row. COUNT(column) counts only rows where that column has a value.
COUNT(*) counts every row. COUNT(column) counts only rows where that column has a value.
6. In SQL, which wildcard matches exactly one character?
- %
- _
- *
- ?
Show the answer
Answer: _
In SQL LIKE patterns, _ matches one character and % matches any number.
In SQL LIKE patterns, _ matches one character and % matches any number.
7. What does index=False do in to_csv()?
- Removes the header
- Stops the row numbers being written
- Sorts the file
- Skips missing values
Show the answer
Answer: Stops the row numbers being written
Without it, pandas writes the DataFrame index as an extra first column.
Without it, pandas writes the DataFrame index as an extra first column.
8. A digital footprint left without the user doing anything deliberately is called
- active
- passive
- encrypted
- anonymous
Show the answer
Answer: passive
The active footprint is what a person posts on purpose; the passive footprint is collected in the background.
The active footprint is what a person posts on purpose; the passive footprint is collected in the background.
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Get it on WhatsApp Book a free demo classPlease read: these are practice questions written by Kwickprep to help you revise. They are not past examination papers and not a CBSE publication. Questions asked in your school’s viva or examination may differ, and the syllabus can change between sessions — the board’s own document at cbseacademic.nic.in is always the final word. Tell us if you spot a mistake and we will correct it.