Class 11 practice
Class 11 reasoning questions.
Reasoning questions for Class 11, at the level of students aged 15–17, each with its answer and a short explanation. Try each one before opening the answer.
In a certain code, consecutive positive integers are paired such that 3 yields 8, 4 yields 15, 5 yields 24, and 6 yields 35. Following this exact rule, what number will 9 yield?
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Answer: 80
Each input number n maps to n squared minus one. For an input of nine, nine squared is eighty-one, and subtracting one gives eighty.
Observe the sequence: 4, 11, 25, 53, 109, ... What number comes next in this pattern?
Level 3 of 5Show the answer
Answer: 221
Each term is obtained by doubling the preceding number and adding 3. Therefore, (109 × 2) + 3 = 218 + 3 = 221.
Five books—Physics, Chemistry, Biology, Mathematics, and History—are stacked vertically. Mathematics is directly above History. Chemistry is placed below Biology but above Mathematics. If Physics is at the very bottom, which book occupies the middle position of the stack?
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Answer: Mathematics
Physics is at the bottom (position 1). With History at 2, Mathematics at 3, Chemistry at 4, and Biology at 5, all conditions are satisfied. Thus, Mathematics is in the middle.
Rohan meets two guides, Dev and Kabir. Dev always tells the truth, whereas Kabir always lies. One guide states: 'At least one of us is a liar.' Which conclusion is logically certain?
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Answer: Dev made the statement.
If Kabir made the statement, it would be a true claim, contradicting his status as a liar. Therefore, only Dev, who tells the truth, could have spoken it.
In a certain code language, KAVERI is written as MYXCTG. Following the exact same letter-shift rule, how should YAMUNA be written?
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Answer: AYOSPY
The code applies alternating shifts of +2 and -2 to each letter. Applying this to YAMUNA produces Y(+2)=A, A(-2)=Y, M(+2)=O, U(-2)=S, N(+2)=P, and A(-2)=Y.
Observe the sequence of numbers: 3, 7, 15, 31, 63, ... Which number comes next in this sequence?
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Answer: 127
Each term is generated by multiplying the preceding term by 2 and adding 1: (63 × 2) + 1 = 127. Alternatively, each term is (2^(n+1) - 1).
Five runners—Jasleen, Gurpreet, Hari, Farhan, and Ishaan—stand in a line facing north. Jasleen stands at the extreme left. Farhan is to the immediate right of Hari. Gurpreet stands between Jasleen and Hari. Who stands in the exact middle?
Level 3 of 5Show the answer
Answer: Hari
From left to right, Jasleen is first, Gurpreet is second, and Hari is third. Because Farhan is immediately to Hari's right, Hari occupies the exact middle of the five positions.
Three runners—Lata, Maya, and Neha—competed in a sprint with no ties. Lata said: 'I did not finish first.' Maya said: 'I finished first.' Neha said: 'Maya did not finish first.' If exactly one statement is true, who won the race?
Level 3 of 5Show the answer
Answer: Lata
Maya and Neha contradict each other, so one of them tells the truth. Therefore, Lata's statement must be false, meaning Lata finished first.
A standard calendar year contains exactly 365 days. If the first day of such a year falls on a Friday, on which day of the week does the final day fall?
Level 3 of 5Show the answer
Answer: Friday
A 365-day year has 52 weeks and 1 day. Exactly 364 days pass between the first and last day. Since 364 is divisible by 7, both days fall on Friday.
Three club members—Kabir, Leela, and Manan—wear badges. Exactly one member wears a silver badge, and two wear bronze badges. Silver badge wearers always tell the truth; bronze wearers always lie. Kabir says, 'Leela wears a bronze badge.' Leela says, 'Manan wears a silver badge.' Who wears the silver badge?
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Answer: Kabir
If Leela wore silver, her statement would make Manan a second silver wearer, which is impossible. Thus, Leela lies and wears bronze. Kabir's statement is true, meaning Kabir wears silver.
A mathematical algorithm generates the sequence: 4, 7, 13, 25, 49, ___. Each successive term is derived using a consistent arithmetic rule. Which number must replace the blank to continue the pattern?
Level 3 of 5Show the answer
Answer: 97
The differences between consecutive terms double each time: +3, +6, +12, +24. The next difference is +48, making the subsequent term 49 + 48 = 97.
Five wooden boxes—V, W, X, Y, and Z—have different weights. Box W is heavier than box V but lighter than box X. Box Y is heavier than box X. Box Z is heavier than box V but lighter than box W. Which box is the third heaviest?
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Answer: Box W
Arranging the boxes in descending order of weight gives Y > X > W > Z > V. The third heaviest box is Box W.
- True or false?
In a class of forty students in Bengaluru, twenty-five study physics and twenty study chemistry. If every student studies at least one of these two subjects, exactly five students must study both subjects.
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Answer: True
By the principle of inclusion-exclusion, the union equals the sum of sets minus their overlap. Here, twenty-five plus twenty minus forty gives five, confirming the number studying both subjects.
- True or false?
During a chess tournament in Chennai, Dev scored higher than Farhan. Later, Farhan scored higher than Gurpreet. Therefore, transitivity guarantees that Dev scored higher than Gurpreet.
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Answer: True
The strict inequality relation 'greater than' is strictly transitive. If A exceeds B and B exceeds C, then A must exceed C.
- True or false?
In formal logic, the converse of a conditional proposition always shares the identical truth value with the original proposition under every circumstance.
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Answer: False
The converse of 'If P, then Q' is 'If Q, then P'. A conditional statement and its converse can have different truth values.
- Fill in the blank.
In the number sequence 2, 6, 12, 20, 30, the next term is ___.
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Answer: 42
The differences between consecutive terms increase by 2 each time (+4, +6, +8, +10); adding 12 to 30 yields 42.
- Fill in the blank.
In an instrument analogy where a thermometer corresponds to temperature, a barometer corresponds directly to atmospheric ___ (first letter: p).
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Answer: pressure
A thermometer measures ambient thermal temperature, whereas a barometer is specifically constructed to measure atmospheric pressure.
- Fill in the blank.
Six students sit in a single row facing north: Tashi sits in position 1, Kabir in position 5, and Deepa precisely halfway between them, placing Deepa in position ___.
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Answer: 3
The midpoint between position 1 and position 5 is calculated as (1 + 5) / 2 = 3.
Which unit of measurement is the odd one out in the International System of Units?
Level 3 of 5Show the answer
Answer: Joule
The ampere, kelvin, and candela are fundamental SI base units. The joule is a derived SI unit used to quantify energy and work.
Which chemical substance is the odd one out based on its acid-base behavior?
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Answer: Sodium oxide
Aluminium oxide, zinc oxide, and lead oxide are amphoteric oxides, reacting with both acids and alkalis, whereas sodium oxide is purely basic.
These questions come from Ado’s question bank and are written with AI help. They are never used in ranked play, so practising them here can’t change anyone’s rank.
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