Answer:check explanation
Step-by-step explanation:1. √25 is a rational number because it is equal to 5, which is a rational number.
2. 4.31 is a rational number because it can be expressed as the ratio of two integers (431/100).
3. -2/2 is a rational number because it can be simplified to -1, which is a rational number.
4. √18 is an irrational number because it cannot be expressed as the ratio of two integers. It is approximately equal to 4.242640687119285.
5. 7 is a rational number because it can be expressed as the ratio of two integers (7/1).
6. Pi is an irrational number because it cannot be expressed as the ratio of two integers or as a terminating or repeating decimal. It is approximately equal to 3.141592653589793.
7. √50 is an irrational number because it cannot be expressed as the ratio of two integers. It is equal to √(25*2) which simplifies to 5√2.
8. -5 is a rational number because it can be expressed as the ratio of two integers (-5/1).
9. 1/3 is a rational number because it can be expressed as the ratio of two integers (1/3 = 0.33333...).
10. 0 is a rational number because it can be expressed as the ratio of two integers (0/1).