Q. Which one of the following non-metals is not a poor conductor of electricity? (UPSC Prelims 2007)
Answer: Selenium
Notes: While most non-metals are poor conductors of electricity, selenium is an exception classified as a semiconductor with moderate electrical conductivity. Semiconductors like selenium display moderate conductivity due to their electron structure, unlike sulphur, bromine, and phosphorus, which have very low conductivity and lack free electrons. Selenium's semiconductor properties make it significantly more conductive than the other options, justifying it as the correct answer.