1. How is the complex number $-9i$ best classified?
2. For what value of $k$ is the complex number $4 + (k - 2)i$ a real number? The value of $k$ is ___.
3. For what value of $m$ is the complex number $(m + 6) - 8i$ purely imaginary? The value of $m$ is ___.
4. Which of the following numbers is complex but is neither real nor purely imaginary?
5. The number $-23$ can be written in the form $a+bi$. How is this number classified?
6. What is the imaginary part of the complex number $5 - 9i$? The answer is ___.
7. What is the real part of the complex number $-1 - 6i$? The answer is ___.
8. What is the real part of the pure imaginary number $11i$?
9. The real number $-8$ can be written as a complex number. What is its imaginary part?
10. Which of the following is a pure imaginary number?