Question

Can someone help me with a couple of true and false questions?
1. Any number in the form of a+/- bi, where a and b are real numbers and b is not = to 0 is considered a pure imaginary number. (True/False)
2. The minimum value of a function is the smallest y-value of the function. (True/False)
3. i^2= The square root of -1 (True/False)
4. Complex numbers can be graphed on the real xy coordinate plane. (True/False)