Answer:
Trifluoromethane [CHF₃] s a polar molecule.
Step-by-step explanation:
Ethylene [C₂H₄] is nonpolar because the electronegtivity difference between the C and H atom in the C-H bond is less than 0.5, making the C-H bond nonpolar.
Both carbon tetrachloride [CCl₄] and carbon tetrafluoride [CF₄] is nonpolar. The C-F and C-Cl bonds are polar but the structure of both CCl₄ and CF₄is symmetrical, square planar, hence the polarity of each C-Cl and C-F bond in CCl4 and CF4 respectively cancel out each other making the overall molecules nonpolar.
Tetrachloroethylene [Cl₂C=CCl₂] is also nonpolar. C-Cl bond is polar but the stture of the molecule is symmetrical, linear, hence the polarity of each C-Cl cancel out each other making the overall molecules nonpolar.
In trifluoromethane [CHF₃] the C-F bonds are polar but the C-H bond is nonpolar, and the structure of the molecule is unsymmetrical, tetrahedral. So the polarity of the two C-F bonds cancel out each other, but the polarity of the third C-F is not counteracted by the nonpolar C-H bond.