CBSE Class 12 Informatics Practices · Practical viva
CBSE Class 12 Informatics Practices Practical Viva Questions, with Answers
The viva carries marks in the CBSE Class 12 Informatics Practices practical, and it is the part students prepare least. Below are 22 questions examiners actually ask, grouped by topic, each with a short answer you can say out loud.
Pandas Series and DataFrame
1. What is a Series?
Answer: A one-dimensional labelled array. It holds one column of data plus an index.
2. What is the difference between a Series and a DataFrame?
Answer: A Series is one-dimensional, a DataFrame is two-dimensional with rows and columns. A DataFrame can be seen as a collection of Series sharing one index.
3. What is the difference between loc and iloc?
Answer: loc selects by label, iloc selects by integer position.
4. What do head() and tail() do?
Answer: head(n) returns the first n rows, tail(n) the last n. The default is 5.
5. What does the shape attribute return?
Answer: A tuple of (number of rows, number of columns).
6. How do you add a new column to a DataFrame?
Answer: Assign to it by name, for example df['Result'] = values. If the column does not exist it is created.
7. What does describe() show?
Answer: Count, mean, standard deviation, minimum, the quartiles and maximum for every numeric column.
Data handling
1. What is a CSV file?
Answer: A plain text file where each line is a row and values are separated by commas. It can be opened by any spreadsheet program.
2. Which pandas functions read and write a CSV?
Answer: read_csv() reads one into a DataFrame, to_csv() writes one out. Passing index=False stops the row numbers being written.
3. How do you find missing values?
Answer: isnull() marks them True, and isnull().sum() counts them per column. fillna() replaces them and dropna() removes those rows.
4. What is the difference between a bar chart and a histogram?
Answer: A bar chart compares separate categories. A histogram shows how a single numeric quantity is distributed across ranges, so its bars touch.
SQL
1. What is an aggregate function? Name four.
Answer: A function that works on a set of rows and returns one value: COUNT, SUM, AVG, MAX and MIN.
2. What does GROUP BY do?
Answer: It collects rows that share a value into groups, so an aggregate function can be applied to each group separately.
3. What is the difference between DELETE and DROP?
Answer: DELETE removes rows but leaves the table. DROP removes the table itself, structure and all.
4. What is a NULL value? Is it the same as zero?
Answer: NULL means no value has been stored. It is not zero and not an empty string, and it is ignored by aggregate functions other than COUNT(*).
5. What does ORDER BY do by default?
Answer: Sorts ascending. DESC reverses it.
6. What does the LIKE operator do?
Answer: Matches a pattern in text. % stands for any number of characters, _ for exactly one.
Societal impact
1. What is digital footprint?
Answer: The trail of data a person leaves online. The active footprint is what they post deliberately; the passive footprint is collected without them doing anything.
2. What is plagiarism?
Answer: Presenting someone else's work or ideas as your own, without crediting them.
3. What is e-waste and why does it matter?
Answer: Discarded electronic equipment. It contains toxic metals, so it must be recycled properly rather than sent to landfill.
4. What is the difference between a copyright and a trademark?
Answer: Copyright protects an original work such as text, music or code. A trademark protects a name, logo or symbol that identifies a business.
5. What is cyberbullying?
Answer: Using digital means to harass, threaten or humiliate someone. It should be recorded and reported, not answered.
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More questions, the practical file format and the topics examiners come back to — sent on WhatsApp.
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.