Multiple choice general knowledge science & technology The Metal Mercury Is the hardest known metal Is a liqyuid at room temprature Is highly radioactive Is extensively used in aircraft construction Reveal answer Fill a bubble to check yourself B Correct answer Explanation Mercury is the only metal that is liquid at room temperature, with a melting point of approximately -38.83°C. This unique physical property makes it easily distinguishable from other metals. Option B is correct despite the typo.