Step 1: Understanding the Question:
In "Odd One Out" questions, we must find a characteristic shared by four of the options that the fifth one lacks.
Step 2: Detailed Explanation:
Analyzing Petrol, Acetone, Kerosene, and Propane: All these substances are organic compounds or mixtures of organic compounds.
- Petrol and Kerosene are mixtures of hydrocarbons derived from petroleum.
- Acetone is a simple organic ketone (\(CH_3COCH_3\)).
- Propane is a three-carbon alkane (\(C_3H_8\)).
- Importantly, all these are highly flammable fuels or solvents.
Analyzing Mercury: Mercury is a chemical element with the symbol \(Hg\) and atomic number 80. It is a heavy, silvery-white metal that is liquid at standard conditions for temperature and pressure. It is an inorganic metal.
Comparison: Four options are organic substances/fuels/hydrocarbons. Mercury is the only inorganic metallic element in the list. Furthermore, while the others are combustible or organic solvents, mercury is non-combustible and a metal.
Step 3: Final Answer:
Mercury is the odd one out because it is a metal, while the others are organic compounds/fuels.