Conceptual MCQs on Prime Time Chapter
CBSE Class 6 Mathematics โ Conceptual MCQs with Answers & Explanations
Chapter 5: Prime Time
Topic: Conceptual MCQs on Prime Time Chapter
Strictly Based on NCERT | Latest CBSE Curriculum
CBSE Board Examination Preparation โ Class 6 Mathematics
1. Which of the following numbers is a prime number?
Correct Answer: C
Explanation: A prime number has exactly two factors: 1 and itself. 13 has only 1 and 13 as factors. 9 = 3ร3 and 21 = 3ร7, so they are composite.
Explanation: A prime number has exactly two factors: 1 and itself. 13 has only 1 and 13 as factors. 9 = 3ร3 and 21 = 3ร7, so they are composite.
2. Why is 1 not considered a prime number?
Correct Answer: B
Explanation: Prime numbers must have exactly two distinct factors. 1 has only one factor (1 itself), so it is neither prime nor composite.
Explanation: Prime numbers must have exactly two distinct factors. 1 has only one factor (1 itself), so it is neither prime nor composite.
3. The smallest prime number is:
Correct Answer: B
Explanation: 2 has exactly two factors (1 and 2). It is also the only even prime number.
Explanation: 2 has exactly two factors (1 and 2). It is also the only even prime number.
4. Which of the following numbers has exactly three factors?
Correct Answer: A
Explanation: Factors of 4 are 1, 2, 4 (three factors). A number with exactly three factors is always the square of a prime number.
Explanation: Factors of 4 are 1, 2, 4 (three factors). A number with exactly three factors is always the square of a prime number.
5. Which pair are co-prime numbers?
Correct Answer: C
14 factors:1,2,7,14 and 15 factors:1,3,5,15. Common factor is only 1.
14 factors:1,2,7,14 and 15 factors:1,3,5,15. Common factor is only 1.
6. Prime factorization of 100:
Correct Answer: A
100รท2=50รท2=25=5ร5.
100รท2=50รท2=25=5ร5.
7. The number 37 is:
Correct Answer: B
No divisors other than 1 and 37.
No divisors other than 1 and 37.
8. Which number is composite?
Correct Answer: D
25=5ร5.
25=5ร5.
9. A number divisible by 2 and 3 must be divisible by:
Correct Answer: B
LCM of 2 and 3 is 6.
LCM of 2 and 3 is 6.
10. The factors of 18 are:
Correct Answer: A
List all divisors of 18.
List all divisors of 18.
11. Prime factorization of 63:
Correct Answer: A.
12. 49 is a square of:
Correct Answer: B.
13. The greatest prime factor of 30 is:
Correct Answer: C.
14. Which number has more factors?
Correct Answer: B
16 has 5 factors.
16 has 5 factors.
15. The product of two prime numbers is always:
Correct Answer: C
Product gives more than two factors.
Product gives more than two factors.
16. Which of the following is not prime?
Correct Answer: C
51=3ร17.
51=3ร17.
17. 2 is called the only:
Correct Answer: B.
18. Prime factorization of 90:
Correct Answer: A.
19. A number divisible by 9 must also be divisible by:
Correct Answer: B.
20. The LCM of 4 and 6 is:
Correct Answer: B
Multiples of 4: 4,8,12โฆ Multiples of 6: 6,12โฆ Common smallest is 12.
Multiples of 4: 4,8,12โฆ Multiples of 6: 6,12โฆ Common smallest is 12.
