- A
Group By
Why wrong: Group By aggregates data based on columns; it does not address null values in a single column.
- B
Remove Duplicates
Why wrong: Remove Duplicates eliminates duplicate rows, but does not affect null values.
- C
Remove Rows -> Remove Blank Rows
Why wrong: Remove Blank Rows only removes rows where every column is null. If other columns have data, rows with null ProductID remain, so the requirement is not met.
- D
Replace Values -> Replace null with a default value
Correct. Replace Values can replace null in the ProductID column with a default value, ensuring no nulls remain in that column.
Question 356 of 966
PL-300 Null handling in Power Query Practice Question
This PL-300 practice question tests your understanding of prepare the data. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. A key principle to apply: null handling in Power Query. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
You are preparing data for a Power BI report. You have a table that contains a 'ProductID' column with some null values. You need to ensure that the 'ProductID' column does not contain any null values in the data model. Which Power Query transformation should you apply?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Replace Values -> Replace null with a default value
Option D is correct because replacing null values with a default value directly ensures that the ProductID column has no nulls in the data model. This transformation can be applied to a specific column using 'Replace Values' in Power Query, where you replace null with a chosen default. Options A and B do not address null values. Option C, 'Remove Blank Rows', only removes rows where all columns are blank, so rows with data in other columns but null ProductID remain, failing the requirement.
Key principle: Null handling in Power Query
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Group By
Why it's wrong here
Group By aggregates data based on columns; it does not address null values in a single column.
- ✗
Remove Duplicates
Why it's wrong here
Remove Duplicates eliminates duplicate rows, but does not affect null values.
- ✗
Remove Rows -> Remove Blank Rows
Why it's wrong here
Remove Blank Rows only removes rows where every column is null. If other columns have data, rows with null ProductID remain, so the requirement is not met.
- ✓
Replace Values -> Replace null with a default value
Why this is correct
Correct. Replace Values can replace null in the ProductID column with a default value, ensuring no nulls remain in that column.
Related concept
Null handling in Power Query
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap is thinking that 'Remove Blank Rows' removes rows with any null in a column; actually it only removes rows where every cell in the row is null. For a specific column like ProductID, filtering rows where ProductID is null or replacing nulls are the correct approaches.
Detailed technical explanation
How to think about this question
In Power Query, 'Remove Blank Rows' uses Table.SelectRows with a condition that checks if all columns in a row are null, which is different from removing rows where a specific column is null. To remove rows with null in a specific column, you would use 'Remove Rows' -> 'Remove Rows with Errors' or filter the column to exclude nulls. Under the hood, Power Query's M language uses Table.SelectRows with a custom condition like each [ProductID] <> null to filter out nulls. A real-world scenario is when ProductID is a foreign key and nulls would break relationships; replacing with a default value like 'Unknown' is often preferred over deleting rows to preserve data integrity.
KKey Concepts to Remember
- Null handling in Power Query
- Replace Values
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Null handling in Power Query
Real-world example
How this comes up in practice
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Null handling in Power Query Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Review null handling in Power Query, then practise related PL-300 questions on the same topic to reinforce the concept.
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FAQ
Questions learners often ask
What does this PL-300 question test?
Prepare the data — This question tests Prepare the data — Null handling in Power Query.
What is the correct answer to this question?
The correct answer is: Replace Values -> Replace null with a default value — Option D is correct because replacing null values with a default value directly ensures that the ProductID column has no nulls in the data model. This transformation can be applied to a specific column using 'Replace Values' in Power Query, where you replace null with a chosen default. Options A and B do not address null values. Option C, 'Remove Blank Rows', only removes rows where all columns are blank, so rows with data in other columns but null ProductID remain, failing the requirement.
What should I do if I get this PL-300 question wrong?
Review null handling in Power Query, then practise related PL-300 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
Null handling in Power Query
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Last reviewed: Jun 11, 2026
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