Which of the following is a wrong way to express 0.5?

The correct answer demonstrates a misunderstanding of numeric representation. While 5.0 does represent a value, it is not equivalent to 0.5. The number 5.0 stands for five, whereas 0.5 indicates one-half or a fraction of one. In contrast, the other options represent the same quantity in different formats. For instance, both 0.5 and .5 are valid numerical expressions of the same value, and even though they look different in format, they are equivalent. Thus, the error lies in identifying 5.0 as representative of 0.5, which it is not, making that choice the incorrect way to express 0.5.