Final answer:
It is true that web addresses or URLs can be written using hexadecimal values through a process called percent-encoding, which represents special characters in URIs.
Step-by-step explanation:
The statement that web addresses or URLs can be written using hexadecimal values is true. URLs can include hexadecimal values as part of what's known as percent-encoding or URL encoding. This is a method used in encoding information in a Uniform Resource Identifier (URI) under certain circumstances. By using a percent sign (%) followed by two hexadecimal digits, characters that aren't typically allowed in a URL can be represented. For example, a space in a URL is encoded as '%20' since the hexadecimal value for a space in ASCII is 20.