$\dfrac{0}{5}$ is a rational number, $\dfrac{0}{8}$ is a rational number, then $\dfrac{0}{5} ÷ \dfrac{0}{8}$ is:

1. an irrational number

2. a rational number

3. 0

4. undefined

a and b are two rational numbers such that a + b = 0; then :

1. a = b

2. a and b are numerically equal

3. a and b are numerically equal but opposite in sign

4. none of the above

The sum of rational number $\dfrac{2}{3}$ and its reciprocal is:

1. 1

2. $2\dfrac{1}{6}$

3. 0

4. $\dfrac{5}{6}$

The product of two rational numbers is -1, if one of them is $\dfrac{2}{5}$, then the other is :

1. $-\dfrac{2}{5}$

2. $\dfrac{5}{2}$

3. $-\dfrac{5}{2}$

4. none of these