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CBSE Important Questions for class 8 Maths chapter Rational Numbers

Important Questions for CBSE Class 8 Maths

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Rational Number

Short Answer Type Questions

  • Q1. What are the multiplicative and additive identities of rational numbers?
  • Ans. 0 and 1 are rational numbers' additive and multiplicative identities.
  • Q2. Write the additive inverse of 19/-6 and -2/3
  • Ans. 19/-6 = 19/6 and -⅔ = 2/3
  • Q3. Write the multiplicative inverse of -13/19 and -7
  • Ans. -13/19 = -19/13 and -7 = -1/7
  • Q4. Mention a rational number that has no reciprocal.
  • Ans. A rational number “0” has no reciprocal or multiplicative inverse.
  • Q5. Mention any 4 rational numbers which are less than 5.
  • Ans. -1, 1, 2 and 3.

Long Answer Type Questions

  • Q6. Mention the commutativity, associative and distributive properties of rational numbers. Also, check a × b = b × a and a + b = b + a for a = 1/2 and b = 3/4
  • Ans. Commutative property:
    • For any two rational numbers, a and b, a + b = b + a.
    • For any two rational numbers, a and b, a × b = b × a.
    • Associative Property:
    • For any three rational numbers a, b and c,
    • (a + b) + c = a + (b + c)
    • Distributive property states that for any three numbers x, y and z,
    • x × ( y + z ) = (x × y) + ( x × z)
    • a x b = b x a
    • a x b = 1/2 x 3/4 = 3/8
    • b x a = 3/4 x 1/2 = 3/8
    • a + b = 3/4 + 1/2 = 5/4
    • b + a = 1/2 + 3/4= 5/4
  • Q7. Write any 5 rational numbers between −2/5 and ½.
  • Ans. −2/5 can be written as −8/20.
    • 1/2 can be written as 10/20.
    • So, rational numbers between these two numbers can be,
    • −7/20,−6/20,−5/20,−4/20,−3/20,−2/20,−1/20,0,1/20,2/20,3/20,4/20.
  • Q8. If the product of any two rational numbers is two and one is 1/7, find the other?
  • Ans. Consider two rational numbers: "a" and "b."
    • Given, a = 1/7 and a × b = 2
    • Now, 1/7 × b = 2
    • b = 7 × 2 = 14
    • So, the other rational number will be 14.
  • Q9. Mr. X went shopping with a certain amount of money. He spent Rs. 10(¼) on buying a pen and Rs. 25(¾) in food. He then gave the remaining Rs. 16(½) to his friend. Calculate how much money he initially had.
  • Ans. To get the amount of money Mr. X initially had, his purchases must be added.
    • So,
    • Initial Money = 10(¼) + 25(¾) + 16(½)
    • = 41/4 + 103/4 + 33/2
    • By taking LCM, we get
    • Initial Money = 105/2

Find below Important Questions for class 8 Maths chapter 1 Rational Numbers

CBSE Important Questions for class 8 Maths chapter Rational Numbers

CBSE Important Questions for class 8 Maths chapter Rational Numbers

CBSE Important Questions for class 8 Maths chapter Rational Numbers

CBSE Important Questions for class 8 Maths chapter Rational Numbers

CBSE Important Questions for class 8 Maths chapter Rational Numbers

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