While researching a topic, a student has taken the following notes:Chemical leavening agents cause carbon dioxide to be released within...
GMAT Expression of Ideas : (Expression) Questions
While researching a topic, a student has taken the following notes:
- Chemical leavening agents cause carbon dioxide to be released within a liquid batter, making the batter rise as it bakes.
- Baking soda and baking powder are chemical leavening agents.
- Baking soda is pure sodium bicarbonate.
- To produce carbon dioxide, baking soda needs to be mixed with liquid and an acidic ingredient such as honey.
- Baking powder is a mixture of sodium bicarbonate and an acid.
- To produce carbon dioxide, baking powder needs to be mixed with liquid but not with an acidic ingredient.
The student wants to emphasize a difference between baking soda and baking powder. Which choice most effectively uses relevant information from the notes to accomplish this goal?
To make batters rise, bakers use chemical leavening agents such as baking soda and baking powder.
Baking soda and baking powder are chemical leavening agents that, when mixed with other ingredients, cause carbon dioxide to be released within a batter.
Baking soda is pure sodium bicarbonate, and honey is a type of acidic ingredient.
To produce carbon dioxide within a liquid batter, baking soda needs to be mixed with an acidic ingredient, whereas baking powder does not.
Step 1: Decode and Map the Passage
Part A: Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| "Chemical leavening agents cause carbon dioxide to be released within a liquid batter, making the batter rise as it bakes." |
|
| "Baking soda and baking powder are chemical leavening agents." |
|
| "Baking soda is pure sodium bicarbonate." |
|
| "To produce carbon dioxide, baking soda needs to be mixed with liquid and an acidic ingredient such as honey." |
|
| "Baking powder is a mixture of sodium bicarbonate and an acid." |
|
| "To produce carbon dioxide, baking powder needs to be mixed with liquid but not with an acidic ingredient." |
|
Part B: Passage Architecture & Core Elements
Main Point: Chemical leavening agents like baking soda and baking powder both make batters rise by releasing carbon dioxide, but they have different compositions and activation requirements.
Argument Flow: The notes first define chemical leavening agents and their function, then identify two specific types. They proceed to detail each type's composition and specific requirements for activation, highlighting the key difference in whether an external acid is needed.
Step 2: Interpret the Question Precisely
What's being asked? Which choice best emphasizes a difference between the two leavening agents
What type of answer do we need? A statement that highlights a contrast/difference between baking soda and baking powder
Any limiting keywords? "emphasize a difference" - we need to focus on contrasting features, not similarities
Step 3: Prethink the Answer
- Looking at our notes, the key difference between baking soda and baking powder is their activation requirements:
- Baking soda needs liquid AND an acidic ingredient to produce CO₂
- Baking powder needs only liquid (no acidic ingredient needed) to produce CO₂
- This is the most significant distinguishing feature. The right answer should clearly contrast their different activation requirements, specifically mentioning that baking soda needs an acidic ingredient while baking powder does not.
To make batters rise, bakers use chemical leavening agents such as baking soda and baking powder.
✗ Incorrect
- This choice simply states that both are chemical leavening agents used to make batters rise
- It focuses on similarities rather than differences and doesn't emphasize any distinction between the two agents
Baking soda and baking powder are chemical leavening agents that, when mixed with other ingredients, cause carbon dioxide to be released within a batter.
✗ Incorrect
- Again focuses on what both agents have in common (both cause \(\mathrm{CO_2}\) release when mixed with ingredients)
- Doesn't highlight any specific difference between them
Baking soda is pure sodium bicarbonate, and honey is a type of acidic ingredient.
✗ Incorrect
- While it mentions baking soda's composition and gives an example of an acidic ingredient, it doesn't establish a clear contrast with baking powder
- Doesn't explain how this relates to their different uses or requirements
To produce carbon dioxide within a liquid batter, baking soda needs to be mixed with an acidic ingredient, whereas baking powder does not.
✓ Correct
- Directly contrasts the activation requirements: baking soda needs an acidic ingredient, baking powder does not
- Uses the key differentiating information from our notes
- The word "whereas" explicitly signals the contrast the question asks for
- This matches our prethinking perfectly