Class 8 Rational Number

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  • 1/15 Questions

    4.  Which of the following is the Multiplicative identity for rational numbers?

    •  I.   1
    • II.   -1
    • III.   0
    • IV.   None of these
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About This Quiz

This CLASS 8 RATIONAL NUMBER quiz assesses understanding of rational numbers through problems on addition, subtraction, and identification of multiplicative identities. It's designed for Class 8 students to strengthen their mathematical skills and rational number concepts.

Class 8 Rational Number - Quiz

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  • 2. 

    3.  Which of the following is the identity element for multiplication?

    •  I.   1

    • II.   -1

    • III.   0

    • IV.   None of these

    Correct Answer
    A.  I.   1
    Explanation
    In mathematics, the identity element is a special element within a set with a particular operation that leaves other elements unchanged when combined with them using that operation. For multiplication, the identity element is 1 because any number multiplied by 1 remains unchanged. In the context of the given options:

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  • 3. 

    6. What number should be added to 3/8 to get -1/24? 

    • (a) -5/12

    • (b) -7/23

    • (c) 31/72

    • (d) 2/33

    Correct Answer
    A. (a) -5/12
    Explanation
    To find the number that should be added to 3/8 to get -1/24, we need to set up an equation. Let x be the number we are looking for. The equation is: 3/8 + x = -1/24. To solve for x, we can first find a common denominator for 8 and 24, which is 24. Multiplying both sides of the equation by 24, we get: 3(3) + 24x = -1. Simplifying, we have: 9 + 24x = -1. Next, subtracting 9 from both sides, we get: 24x = -10. Finally, dividing both sides by 24, we find that x = -10/24, which simplifies to -5/12. Therefore, the correct answer is (a) -5/12.

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  • 4. 

    8. Simplify: 2/3 + -4/5 + 7/15 + -11/20

    • (a) -1/5

    • (b) -13/60

    • (c) -4/15

    • (d) – 7/30

    Correct Answer
    A. (b) -13/60
    Explanation
    To simplify the given expression, we need to find the common denominator for all the fractions. The common denominator is 60. Then, we can add the fractions together.

    2/3 can be written as 40/60
    -4/5 can be written as -48/60
    7/15 can be written as 28/60
    -11/20 can be written as -33/60

    Adding all the fractions together, we get:
    40/60 + (-48/60) + 28/60 + (-33/60) = -13/60

    Therefore, the correct answer is (b) -13/60.

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  • 5. 

    5. The sum of the rational numbers – 8/19 and -4/57 is _____

    • (a) -5/57

    • (b) 7/22

    • (c) -28/57

    • (d) 4/27

    Correct Answer
    A. (c) -28/57
    Explanation
    The sum of two rational numbers can be found by adding their numerators and keeping the same denominator. In this case, the numerator of the first rational number is -8 and the numerator of the second rational number is -4. Adding these two numerators gives -8 + (-4) = -12. The denominator remains the same, which is 57. Therefore, the sum of the rational numbers -8/19 and -4/57 is -12/57, which can be simplified to -4/19. However, none of the given options match this simplified fraction. Therefore, the correct answer is (c) -28/57.

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  • 6. 

    What should be subtracted from -5/4 to get -1?

    •  I.   -1/4

    • II.   1/4

    • III.   1

    • IV.   -3/4

    Correct Answer
    A.  I.   -1/4
  • 7. 

    10. Which of the following rational numbers is in the standard form?

    • (a) -9/28

    • (b) -26/78

    • (c) –14/16

    • (d) 48/-96

    Correct Answer
    A. (a) -9/28
    Explanation
    The standard form of a rational number is when the numerator and denominator have no common factors other than 1. In option (a), -9/28, the numerator and denominator do not have any common factors other than 1, making it the rational number in standard form.

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  • 8. 

    11. The sum of two rational numbers is -7. If one of the numbers is –15/19, the other number is _____

    • (a) -21/10

    • (b) -57/16

    • (c) 7/9

    • (d) -118/19

    Correct Answer
    A. (d) -118/19
    Explanation
    The sum of two rational numbers is -7. If one of the numbers is -15/19, we can find the other number by subtracting -15/19 from -7. This can be done by finding a common denominator, which is 19 in this case. So, -7 can be written as -133/19. Subtracting -15/19 from -133/19 gives us -118/19. Therefore, the other number is -118/19.

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  • 9. 

    1.  What should be added to -5/4 to get -1?

    •  I.   -1/4

    • II.   1/4

    • III.   1

    • IV.   -3/4

    Correct Answer
    A. II.   1/4
    Explanation
    .

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  • 10. 

    9. What number should be subtracted from -3/4 so as to get 5/6?

    • (a) -3/10

    • (b) -5/24

    • (c) -19/12

    • (d) 9/25

    Correct Answer
    A. (c) -19/12
    Explanation
    .

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  • 11. 

    13. The value of (- 16/21 ÷ -4/3) is _____

    Correct Answer
    4/7
    Explanation
    The value of (-16/21 ÷ -4/3) can be found by multiplying the numerator of the first fraction (-16/21) by the reciprocal of the second fraction (-3/4). This gives us (-16/21) * (-3/4) = 48/84, which can be simplified to 4/7. Therefore, the correct answer is 4/7.

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  • 12. 

    7. Which of the rational numbers 4/9, -5/6, -7/-12 and 11/-24 is the smallest?

    • (a) 4/9

    • (b) -5/6

    • (c) -7/-12

    • (d) 11/-24

    Correct Answer
    A. (b) -5/6
    Explanation
    To determine the smallest rational number among 4/9, -5/6, -7/-12, and 11/-24, we need to compare their values. Since all the given rational numbers are negative, the larger the numerator and the smaller the denominator, the smaller the value of the rational number. Comparing the numerators, -5 is smaller than 4 and 11. Comparing the denominators, 6 is smaller than 9 and 24. Therefore, -5/6 is the smallest rational number among the given options.

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  • 13. 

    12. Which of the following forms a pair of equivalent rational numbers?

    • (a) 24/40 and 35/50

    • (b) -25/35 and 55/-77

    • (c) -8/15 and -24/48

    • (d) 9/72 and -3/21

    Correct Answer
    A. (b) -25/35 and 55/-77
    Explanation
    The pair of rational numbers -25/35 and 55/-77 is equivalent because they can be simplified to -5/7 and -5/7 respectively. Both fractions have the same numerator and denominator, resulting in an equivalent ratio.

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  • 14. 

    15. The product of two numbers is -20/9. If one of the numbers is 4, find the other. 

    Correct Answer
    -5/9
    Explanation
    If the product of two numbers is -20/9 and one of the numbers is 4, we can find the other number by dividing -20/9 by 4. Dividing -20/9 by 4 gives us -5/9. Therefore, the other number is -5/9.

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  • 15. 

    14. Fill in the blanks: 5/12 ÷ (_____) = -35/18

    Correct Answer
    -3/14
    Explanation
    To find the missing value in the division equation, we need to divide 5/12 by a number that gives us -35/18 as the result. The answer is -3/14 because when we divide 5/12 by -3/14, we get -35/18.

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  • Jan 14, 2025
    Quiz Edited by
    ProProfs Editorial Team
  • May 16, 2020
    Quiz Created by
    Chunni Pandit
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