#### Answer

a. $\sqrt 4$
b. 0, $\sqrt 4$
c. -5, 0, $\sqrt 4$
d. -5, -$\frac{3}{9}$ (the fraction expression of -0.3 repeating), 0, $\sqrt 4$
e. $\sqrt 2$
f. -5, -$\frac{3}{9}$, 0, $\sqrt 2$, $\sqrt 4$

#### Work Step by Step

a. Natural numbers are all positive numbers. The square root of 4 is equal to 2 ($\sqrt 4$=2).
b. Whole numbers are all natural numbers and 0.
c. Integers are all whole numbers and the negatives of the natural numbers.
d. Rational numbers can be expressed as a fraction of two integers in which the denominator cannot equal 0. They can also be expressed as repeating decimals. -5 can be expressed as -$\frac{5}{1}$, 0 can be expressed as $\frac{0}{1}$, and $\sqrt 4$ can be expressed as $\frac{\sqrt 4}{1}$.
e. Irrational numbers are all numbers whose decimal representations are not repeating and thus cannot be expressed as a quotient of integers.
f. Real numbers are all numbers that are either rational or irrational.