Which of the following is the **empty set** $\phi$?
A$\{0\}$
B$\{x : x \text{ is a natural number and } 1 < x < 2\}$
C$\{\phi\}$
D$\{x : x \text{ is a real number and } x^2 = 4\}$
Answer & Solution
Correct answer: B. $\{x : x \text{ is a natural number and } 1 < x < 2\}$
*No natural number lies strictly between 1 and 2* — so set **B** is empty.
- **A** $\{0\}$ contains the element $0$ — not empty.
- **C** $\{\phi\}$ contains one element (the empty set itself) — not empty.
- **D** $\{2, -2\}$ has two elements.
Related questions
Direct: The mother said, 'Sleep now, my child.' Indirect form isDirect: She said to him, 'Can you help me?' Indirect form isDirect: She said, 'May God bless you!' Indirect form isDirect: The boy said, 'Alas! I have failed.' Indirect form isDirect: He said, 'I bought this book yesterday.' Indirect form isDirect: He said, 'I will see you tomorrow.' Indirect form isDirect: She said, 'Hurrah! We have won the match.' Indirect form isDirect: He said to her, 'Please help me.' Indirect form is