Write 23 in scientific notation a. 23 x 101 b. 2.3 x 101 c. 2.3 x 102 d. 2.3 x 103

When using scientific notation, you only want one number to be in front of the decimal place. If you have to make the number smaller, then the 10^nth power will be positive. If you have to make the number bigger, then 10^nth power will be negative. Example:
0.54 --> 5.4 * 10^-1
35 --> 3.5 * 10^1
The value of n depends on how many spaces the decimal point needs to be moved. For your question, putting 23 in scientific notation would look like this:
23 --> 2.3 * 10^1