If x is a positive rational number which is not a perfect square, then $-5\sqrt{x}$ is

1. a negative integer
2. an integer
3. a rational number
4. an irrational number

If x, y are both positive rational numbers, then $(\sqrt{x} + \sqrt{y})(\sqrt{x} - \sqrt{y})$ is

1. a rational number
2. an irrational number
3. neither rational nor irrational number
4. both rational as well as irrational number

The number obtained on rationalising the denominator of ${\dfrac{1}{\sqrt{7} - 2}}$ is

1. ${\dfrac{\sqrt{7} + 2}{3}}$

2. ${\dfrac{\sqrt{7} - 2}{3}}$

3. ${\dfrac{\sqrt{7} + 2}{5}}$

4. ${\dfrac{\sqrt{7} + 2}{45}}$

The number $0.\overline{25}$ is equal to

1. $\dfrac{65}{99}$

2. $\dfrac{37}{99}$

3. $\dfrac{5}{9}$

4. $\dfrac{25}{99}$