Place the following substances in order of increasing vapour pressure at a given temperature. SF₆ SiH₄ SF₄ A) SF₆

Question

Place the following substances in order of increasing vapour pressure at a given temperature. SF₆ SiH₄ SF₄ A) SF₆ < SiH₄< SF₄ B) SiH₄ < SF₄ < SF₆ C) SF₆< SF₄< SiH₄ D) SF₄ < SF₆ < SiH₄ E) SiH₄ < SF₆< SF₄

Quizplus · Accepted Answer

Vapour pressure increases with decreasing boiling points. All three substances are compounds of sulfur and silicon. SiH₄ has the highest boiling point due to the presence of Si-H bonds, while both SF₆ and SF₄ lack such strong intermolecular forces. Among SF₆ and SF₄, the latter has a lower boiling point due to the smaller size of the substituent (fluorine vs chloride). Therefore, the correct order of increasing vapour pressure is SF₄ < SF₆ < SiH₄, which is option D.

Place the Following Substances in Order of Increasing Vapour Pressure