Which compound has the chemical formula CHCl3 whose melting point is 209 K? A. Carbon tetrachloride B. Chlorophenol C. Chloroform D. Chloroethanol

Carbon tetrachloride
Chlorophenol
Chloroform
Chloroethanol

The correct answer is $\boxed{\text{chloroform}}$.

Chloroform is a chemical compound with the chemical formula CHCl3. It is a colorless, dense, and highly volatile liquid that is widely used as a solvent. Chloroform is also a powerful anesthetic and was once used in medicine, but it is now known to be a carcinogen and is no longer used for this purpose.

The melting point of chloroform is 209 K, which is equivalent to -73.5 °C. This means that chloroform will melt at a temperature of -73.5 °C and will turn into a liquid.

The other options are incorrect because they do not have the chemical formula CHCl3.

  • Carbon tetrachloride has the chemical formula CCl4. It is a colorless, non-flammable liquid that is used as a solvent and refrigerant. The melting point of carbon tetrachloride is 250 K, which is equivalent to -23 °C.
  • Chlorophenol has the chemical formula C6H5ClO. It is a white, crystalline solid that is used as a disinfectant and herbicide. The melting point of chlorophenol is 295 K, which is equivalent to 22 °C.
  • Chloroethanol has the chemical formula C2H5ClOH. It is a colorless, flammable liquid that is used as a solvent and intermediate in the manufacture of other chemicals. The melting point of chloroethanol is 243 K, which is equivalent to -26 °C.