Question 1

Which one of the following is the odd one out?
Pencil, Pen, Eraser, Sharpener

Accepted Answer

Pencil, Pen, and Sharpener are all writing/maintenance instruments used with pencils. Eraser is used to remove marks made by pencil, but it is not a writing instrument itself—it serves a different primary function (correction rather than writing or maintaining writing tools).

Question 2

Which one of the following is the odd one out?
Sparrow, Eagle, Penguin, Parrot

Accepted Answer

Sparrow, Eagle, and Parrot are all birds that can fly. Penguin is a bird that cannot fly—it is flightless and adapted for swimming instead.

Question 3

Which one of the following is the odd one out?
Apple, Carrot, Potato, Spinach

Accepted Answer

Apple is a fruit that grows on trees. Carrot, Potato, and Spinach are all vegetables—specifically, they are parts of plants grown underground or as leafy greens for consumption.

Question 4

Which one of the following is the odd one out?
Dog, Cat, Cow, Parrot

Accepted Answer

Dog, Cat, and Cow are all mammals—they have fur/hair, produce milk for their young, and are warm-blooded vertebrates. Parrot is a bird—it has feathers, lays eggs, and is a different class of vertebrate.

Question 5

Find the odd one out:
Tomato, Carrot, Potato, Pumpkin

Accepted Answer

Tomato is the odd one out because it is botanically a fruit (develops from the flower's ovary), while Carrot, Potato, and Pumpkin are all vegetables. Carrot is a root vegetable, Potato is a tuber, and Pumpkin is a squash/gourd—all are vegetables by culinary and botanical classification. Tomato, though culinarily used as a vegetable, is botanically a fruit.

Question 6

Find the odd one out:
Diamond, Emerald, Ruby, Coal

Accepted Answer

Coal is the odd one out because it is an organic sedimentary rock formed from decomposed plant matter, while Diamond, Emerald, and Ruby are all precious gemstones formed through geological processes under extreme pressure and heat. Coal is not classified as a gemstone and has significantly lower value and hardness compared to the other three.

Question 7

Find the odd one out:
Microphone, Speaker, Headphones, Amplifier

Accepted Answer

Microphone is the odd one out because it is an input device that converts sound into electrical signals, while Speaker, Headphones, and Amplifier are all output devices. Speaker and Headphones convert electrical signals back into sound; Amplifier increases the strength of electrical signals for output. Microphone operates on the opposite principle—capturing sound rather than producing it.

Question 8

Find the odd one out:
Anchor, Satellite, Comet, Asteroid

Accepted Answer

Anchor is a man-made object used for mooring ships, while Satellite, Comet, and Asteroid are all celestial bodies found in space. Anchor is the odd one out because it is the only non-astronomical object.

Question 9

Find the odd one out:
Pencil, Eraser, Sharpener, Notebook

Accepted Answer

Pencil, Eraser, and Sharpener are all tools/accessories used to maintain or modify writing instruments, while Notebook is a surface/medium for writing. Notebook is the odd one out because it serves a different functional purpose.

Question 10

Find the odd one out:
Lion, Tiger, Cheetah, Leopard

Accepted Answer

Lion is the only social feline that lives in groups (prides), while Tiger, Cheetah, and Leopard are all solitary hunters. Lion is the odd one out based on social behavior.

Question 11

Find the odd one out:
Microphone, Speaker, Amplifier, Headphones

Accepted Answer

Microphone is an input device that converts sound into electrical signals, while Speaker, Amplifier, and Headphones are all output devices that convert electrical signals into sound. Microphone is the odd one out based on signal direction.

Question 12

Find the odd one out:
Rose, Lotus, Sunflower, Cactus

Accepted Answer

Rose, Lotus, and Sunflower are all flowering plants that require regular watering and grow in moist or well-watered environments, while Cactus is a succulent plant adapted to arid, dry environments with minimal water requirements. Cactus is the odd one out based on habitat and water requirements.

Question 13

Four words are given below. Three of them share a common characteristic. Find the odd one out.
Mercury, Venus, Earth, Moon

Accepted Answer

Mercury, Venus, and Earth are all planets in our Solar System that orbit the Sun. The Moon, however, is a natural satellite (of Earth) — not a planet. Therefore, 'Moon' is the odd one out. A common mistake is choosing Mercury because it is the smallest, but size is not the distinguishing criterion here.

RRB NTPC Classification / Odd One Out

RRB NTPC Classification / Odd One Out — Past Exam Questions

Classification / Odd One Out— Rules & Concept

Key Points to Remember

Exam-Specific Tips

Classification / Odd One Out — Practice Questions

60-Second Revision — Classification / Odd One Out