Logical Reasoning · Series & Analogies
Essential Part — Questions & Answers
Essential part questions ask which item something cannot exist without. The answer is the one part that is always present by definition, not just usually found with it.
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Ask of each option: "Could this thing exist without it?" If yes, the option is only typical. The essential part is the one the thing would stop being itself without.
Think of the dictionary meaning of the keyword. The essential option is part of that meaning; the others describe things that often go with it.
For an activity or event, ask what it cannot happen without: the people taking part, the material it uses, or the process that defines it. Places and tools are usually optional.
Three options are essential and one is only typical. Test each option: if the thing can still exist without it, that option is the answer.
5 solved Essential Part questions
Which of these is essential to a chair?
Solution — answer B
A chair must have a seat to sit on. Many chairs have no cushion, armrests or wheels.
4 steps · reveal one at a timeStep 1: Understand "essential"
We need to identify what a chair absolutely must have to function as a chair. If a part is essential, a chair cannot exist without it.
Step 2: Consider chair components
Think about various types of chairs you've seen. Some chairs have cushions for comfort, but many chairs, like a basic wooden stool or a plastic chair, do not. Similarly, not all chairs have armrests or wheels.
Step 3: Identify the core purpose
The fundamental purpose of a chair is to provide a surface for someone to sit on. Without this core component, it wouldn't serve its primary function.
Step 4: The answer
So the answer is (B) seat. A chair must have a seat to sit on, whereas cushions, armrests, and wheels are optional features.
Which of these is NOT essential to a triangle?
Solution — answer B
Every triangle has three sides, three angles and three corners, but only some triangles have a right angle.
4 steps · reveal one at a timeStep 1: Define a triangle
A triangle is a fundamental geometric shape. It is a polygon with three edges and three vertices. We need to find a property from the options that is not always true for every single triangle.
Step 2: Identify core properties
By its very definition, a triangle must have three straight sides. Where these sides meet, they form three distinct corners (also called vertices). These corners also define the three interior angles of the triangle.
Step 3: Consider angle types
While every triangle has three angles, not all triangles have a specific type of angle. For example, some triangles have all acute angles, some have one obtuse angle, and some have one right angle (90∘).
Step 4: The answer
So the answer is (B) a right angle. Every triangle must have three sides, three angles, and three corners. However, only specific types of triangles (right-angled triangles) possess a right angle, making it not essential for all triangles.
Which of these cannot happen without water?
Solution — answer C
Swimming means moving through water, so it cannot happen without water. Running, reading and singing can.
4 steps · reveal one at a timeStep 1: Understand the Question
We need to identify the activity from the list that cannot happen if there is no water present. Think about what each activity fundamentally involves.
Step 2: Evaluate Activities
Consider activities like running, reading, and singing. Can you do these things without water? Yes, you can run on land, read a book in a room, or sing a song anywhere dry.
Step 3: Focus on the Remaining
Now, think about the activity of swimming. What does it mean to swim? Swimming is defined as moving through water using your body. This definition itself tells us something crucial.
Step 4: The answer
So the answer is (C) swimming. Swimming, by its very definition, involves moving through water, meaning it cannot happen without water.
In which pair is the second item essential to the first?
Solution — answer B
A river cannot exist without water. A river can have no fish, a garden no fountain, and a car no radio.
4 steps · reveal one at a timeStep 1: Understand 'essential'
The question asks for a pair where the second item is essential to the first. This means the first item absolutely cannot exist or function as described without the second item.
Step 2: Evaluate other pairs
Consider other relationships. A river can exist without fish. A garden can exist without a fountain. A car can exist and function without a radio. These items are not essential.
Step 3: Identify the core need
Now, think about a river and water. Can a river exist without water? No, by definition, a river is a natural flowing watercourse. Water is fundamental to its existence.
Step 4: The answer
So the answer is (B) river : water. A river cannot exist without water, making water essential to it. The other pairs do not show this essential relationship.
Without which of these would there be no a pen?
Solution — answer C
A pen writes with ink, so ink is essential. Many pens have no cap or clip, and fountain pens take no refill.
4 steps · reveal one at a timeStep 1: Understand Pen's Function
Think about what a pen is used for. Its main purpose is to write. What does a pen need to accomplish this task?
Step 2: Evaluate Essential Components
A pen writes with ink. Without ink, a pen cannot perform its basic function. Consider if other parts are always necessary.
Step 3: Consider Non-Essential Parts
Many pens do not have a cap (like click pens) or a clip. Fountain pens, for example, do not use a refill in the same way a ballpoint pen does, but they still need ink.
Step 4: The answer
So the answer is (C) ink. A pen's fundamental purpose is to write, and it cannot do this without ink.
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