Question

Which among the following statements are correct?
(a)- ${ XeF }_{ 4 }$ and ${ SbF }_{ 5 }$ combine to form a salt.
(b)- He and Ne do not form clathrates.
(c)- He has the highest boiling point in its group.
(d)- He diffuses through rubber and polyvinyl chloride.

Answer 1

Clathrates compounds are the class of compounds in which any element/ion/molecule is trapped in between the cavities of the crystal lattice of organic or inorganic compounds. In the 18th group, boiling point is proportional to the strength of Van der Waals force of attraction and as the size increases the boiling point increases. Noble gases of small size can diffuse through rubber and PVC.

Complete step by step answer:
(a)- The following reaction will take place when ${ XeF }_{ 4 }$ and ${ SbF }_{ 5 }$ combine;
$Xe{{F}_{4}}+Sb{{F}_{5}}\to \ \ [XeF][Sb{{F}_{6}}]$ which is a salt because the xenon fluoride is the positive part and antimony pentafluoride is the negative part. Hence, this statement is correct.
(b)- Clathrates compounds are the class of compounds in which any element/ion/molecule is trapped in between the cavities of the crystal lattice of organic or inorganic compounds, so the size of the element must be sufficiently large so that they can get trapped. Due to the small sizes of helium and neon can escape from the cavities and hence they do not form clathrate compounds. So, it is a correct statement.
(c)- The van der Waal forces of attraction increase as the size increases down the group. So, the boiling point increases down the group. So, Xe which is the last element of the group has the highest boiling point in its group, and helium is the first element that will have the lowest boiling point.
(d)- One of the properties of Helium is that it diffuses through many substances like silica glass, pyrex chemically resistant glass, rubber, PVC (polyvinyl chloride), etc. And this is due to the small size of the helium atom. The correct answer is option “A,B,C and D” .

Note: In all the groups the boiling point increases as we move down the group because when we move down the size of the atom increases which means the van der Waal forces increases, and boiling point increases down.