All Exams Test series for 1 year @ ₹349 only
Question

If proposition 'All pens are not pencils' is taken to be true, then which of the following propositions can be false?

This question was previously asked in
UGC NET 2019 Paper 1 Question Paper (5-Dec-2019) (Shift 2)
The correct answer is

All pens are pencils

To analyze the given proposition and determine which option can be false, we need to understand the statement and its implications in logical terms.

The given proposition is: "All pens are not pencils." This essentially means that not every pen is a pencil. Another way to interpret this is that at least one pen is not a pencil.

We have four options to evaluate:

  1. All pens are pencils
  2. Some pencils are pens
  3. No pen is pencil
  4. Some pens are pencils

Let's evaluate each option:

  • All pens are pencils: This statement contradicts the given proposition. The proposition states that not all pens are pencils. Therefore, this option must be false.
  • Some pencils are pens: This is possible even if not all pens are pencils. There's no contradiction here, so this statement can be true.
  • No pen is pencil: This is a possible scenario under the given proposition. If no pen is a pencil, then certainly not all pens are pencils. Hence, this statement can also be true.
  • Some pens are pencils: This is possible if not all pens are pencils, implying that some still could be. There is no contradiction, so this statement can also be true.

Based on this evaluation, the option that can be false while the original statement is true is:

  • All pens are pencils

The correct answer is "All pens are pencils," as it directly contradicts the given proposition.

Was this answer helpful?

Similar Questions

  1. Which of the following is contrary to the statement "No mammals are birds"?

  2. If the statement "Some animals are birds" is given as false then which of the following statements can be immediately inferred to be false?

  3. Which of the following propositions can be directly inferred from the statement - "All mammals are four-legged animals?

  4. Which of the following statements are contradictory to each other?

     A. All objects are perishable.

     B. Some objects are not perishable. 

    C. Some objects are perishable. 

    D. No objects are perishable. 

    Choose the most appropriate answer from the options given below:

  5. Among the following propositions two are related in such a way that they cannot both be true but can both be false. Select the code that states those two propositions.

    Propositions:

    (a) Every student is attentive.

    (b) Some students are attentive.

    (c) Students are never attentive.

    (d) Some students are not attentive.

    Codes:

  6. If proposition 'some milk is curd' is taken to be true, then which of the following propositions can be false?

  7. When subject and predicate of both the premises is same but they differ only in quantity, it is known as:

  8. ‘All republics are grateful’ and ‘Some republics are not grateful’ cannot both be true, and they cannot both be false. This is called as

  9. If the proposition ‘Houses are not bricks’ is taken to be False then which of the following propositions can be True?
    (a) All houses are bricks
    (b) No house is brick
    (c) Some houses are bricks
    (d) Some houses are not bricks
    Select the correct answer from the options given below:

  10. Among the following statements, two are contradictory to each other. Select the code that represents them.

    Statements :

    (a) All surgeons are doctors.

    (b) Some surgeons are doctors.

    (c) Some surgeons are not doctors.

    (d) No surgeons are doctors.

    Code


Important Questions from Classical Square of Opposition

  1. Which of the following statements are so related that they can not both be true but could both be false?

    A. All Biologists are outstanding teachers.

    B. Some Biologists are outstanding teachers.

    C. No Biologists are outstanding teachers.

    D. Some Biologists are not outstanding teachers.

    Choose the correct answer from the options given below:

  2. Which of the following is contrary to the statement "No mammals are birds"?

  3. If the statement "Some animals are birds" is given as false then which of the following statements can be immediately inferred to be false?

  4. Which of the following propositions can be directly inferred from the statement - "All mammals are four-legged animals?

  5. Which of the following statements are contradictory to each other?

     A. All objects are perishable.

     B. Some objects are not perishable. 

    C. Some objects are perishable. 

    D. No objects are perishable. 

    Choose the most appropriate answer from the options given below:

Need Expert Advice?
Upcoming Exams
MH SET
October 25, 2026
JTET
November 01, 2026
CTET
December 12, 2026
Test Series
UGC NET img
Teaching
UGC NET (Paper 2) 2026 Mock Test Series
796 Tests 2 Tests Free
4.4(36)
English
More Questions from UGC NET

Start Your Preparation with Prepp Mobile App

Download the app from Google Play & App Store
Download the app from Google Play & App Store
Prepp Mobile App