Chapter-3 A Story of Numbers — Online MCQ Test
MATHS (KANITHA PRAKASH) · CLASS 8th · Karnataka State Board
Practice Chapter-3 A Story of Numbers with a free chapter-wise online MCQ test.
This chapter covers: rational numbers - closure property - commutative property - associative property - distributive property - additive inverse - reciprocal.
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Chapter-3 A Story of Numbers — Important Questions & Answers
Which of the following is a rational number?
- A. 3/4
- B. √2
- C. π
- D. e
Answer: A. 3/4
A rational number is any number that can be expressed as p/q where p and q are integers and q ≠ 0. 3/4 satisfies this definition.
A rational number is any number that can be expressed as p/q where p and q are integers and q ≠ 0. 3/4 satisfies this definition.
What is the additive inverse of -5/7?
- A. -5/7
- B. 5/7
- C. 7/5
- D. -7/5
Answer: B. 5/7
The additive inverse of a number is what you add to it to get 0. Since -5/7 + 5/7 = 0, the additive inverse is 5/7.
The additive inverse of a number is what you add to it to get 0. Since -5/7 + 5/7 = 0, the additive inverse is 5/7.
If 2/3 + x = 0, then x is the ______ of 2/3.
- A. reciprocal
- B. additive inverse
- C. multiplicative inverse
- D. opposite fraction
Answer: B. additive inverse
The additive inverse is the number that when added to another gives 0. Here, x = -2/3, which is the additive inverse of 2/3.
The additive inverse is the number that when added to another gives 0. Here, x = -2/3, which is the additive inverse of 2/3.
Compare the properties: Is the set of rational numbers closed under division?
- A. Yes, division is always possible
- B. No, we cannot divide by zero
- C. Only when both numbers are positive
- D. Only when the divisor is larger
Answer: B. No, we cannot divide by zero
While the quotient of two rational numbers is rational (when the divisor is non-zero), the set is not closed under division because division by zero is undefined.
While the quotient of two rational numbers is rational (when the divisor is non-zero), the set is not closed under division because division by zero is undefined.
(Tricky) Which statement is ALWAYS true for rational numbers?
- A. The product of any two rational numbers is greater than both numbers
- B. The sum of two rational numbers is always greater than each individual number
- C. If a and b are rational, then a/b (where b ≠ 0) is also rational
- D. Every rational number has a multiplicative inverse
Answer: C. If a and b are rational, then a/b (where b ≠ 0) is also rational
The quotient of two rational numbers (when divisor ≠ 0) is always rational. Options A and B fail with examples like 1/2 × 1/3 or negative numbers.
The quotient of two rational numbers (when divisor ≠ 0) is always rational. Options A and B fail with examples like 1/2 × 1/3 or negative numbers.