Chapter Exam

Chapter-3 A Story of Numbers — Online MCQ Test

Q: Which of the following is a rational number?

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.

Q: What is the additive inverse of -5/7?

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.

Q: If 2/3 + x = 0, then x is the ______ of 2/3.

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.

Q: Compare the properties: Is the set of rational numbers closed under division?

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.

MATHS (KANITHA PRAKASH) · CLASS 8th · Karnataka State Board

Practice Chapter-3 A Story of Numbers with a free chapter-wise online MCQ test for Karnataka State Board CLASS 8th MATHS (KANITHA PRAKASH). This chapter covers: rational numbers - closure property - commutative property - associative property - distributive property - additive inverse - reciprocal. AI-generated questions from basic to board-exam level, with instant results and explanations.

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Chapter-3 A Story of Numbers — Important Questions & Answers (FAQ)

Frequently asked questions from Karnataka State Board CLASS 8th MATHS (KANITHA PRAKASH) — Chapter-3 A Story of Numbers, with answers and explanations. These are sample questions; the exam has its own separate question set.

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.

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.

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.

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.

(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.