Question 1

What is the additive identity for rational numbers?

Accepted Answer

The correct answer is 0. Adding 0 to any rational number gives the same rational number ($a + 0 = a$).

Question 2

What is the multiplicative identity for rational numbers?

Accepted Answer

The correct answer is 1. Multiplying any rational number by 1 gives the same rational number ($a 	imes 1 = a$).

Question 3

What is the multiplicative inverse (reciprocal) of $-\frac{5}{9}$?

Accepted Answer

The correct answer is $-\frac{9}{5}$. The multiplicative inverse of a non-zero rational number $\frac{a}{b}$ is $\frac{b}{a}$ because $\frac{a}{b} 	imes \frac{b}{a} = 1$.

Question 4

Which rational number does NOT have a reciprocal?

Accepted Answer

The correct answer is 0. The reciprocal of 0 would be $\frac{1}{0}$, which is undefined.

Question 5

Rational numbers are NOT closed under which of the following operations?

Accepted Answer

The correct answer is Division. Division by zero is not defined, so rational numbers are not closed under division.

Rational Numbers