Which of the following propositions are contradictory? Choose the correct answer from the options given below.

1.All squares are rectangles.

2.No square is a rectangle.

3.Some squares are rectangles.

4.Some squares are not rectangles.

A3, 4 only

B1, 4 only ✓ Correct

C2, 4 only

D1, 2 only

Correct answer: (B) 1, 4 only

Explanation

The contradictory pair here is "All squares are rectangles" and "Some squares are not rectangles".

Statement 1 is the universal affirmative A.

Statement 4 is the particular negative O.

A and O are diagonal on the square of opposition and always oppose in truth value.

If one is true the other must be false, and they can never agree.

This exact opposition of truth values makes Statements 1 and 4 contradictory.

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