[Win,odd Dhamnekar]

1) The group 4 elements have these boiling points when bound to four hydrogens: [itex]CH_4: -162^\circ C, SiH_4: -112^\circ C, GeH_4: -88^\circ C, SnH_4: -52^\circ C[/itex] Explain this increasing trend using your knowledge of intermolecular forces.
2) Which member of the each of the following pairs would you expect to have a higher boiling point, and why?

   [itex] O_2 [/itex]  and [itex]Br_2[/itex]
    [itex]NO_2[/itex] and [itex]CO_2[/itex]
    HF and HCl

3) In climates with cold winters, water pipes have to be taken care of carefully in the winter, especially outside water pipes. Explain why, referencing hydrogen bonds.
4) A cup can filled all the way to the brim, and then even past the rim. Explain why the water doesn’t overflow.

What are the answers to these questions? 

[Babcock_Hall]

It is a forum rule that you must show your attempt at answering a question before we can help you.  A good place to start might be to list out the IMFs that you think are relevant to each question.

[Win,odd Dhamnekar]

My quick answer to question 2) in the pair [itex]O_2(l)[/itex] and [itex]Br_2(l),[/itex] [itex] Br_2[/itex] have higher boiling point. In the pair [itex]NO_2(g)[/itex] and [itex]CO_2(g),[/itex] [itex] NO_2(g)[/itex] have higher boiling point.  In the pair HF(g)and HCL(g), HF(g) have higher boiling point. I have to find out the reasons for higher boiling points of these chemical substances.

 What about answers to other questions? Oh, I am working on it.  

[Babcock_Hall]

What do you know about the relationship between dipole moments ard molecular geometry?

[Win,odd Dhamnekar]

Answer to question 1) Because of London dispersion forces, boiling point of group 14 elements bonded with 4 hydrogen atoms increases with increase in molar mass.

Answer to question 2)In the [itex]O_2[/itex] and [itex] Br_2[/itex] pair,[itex] Br_2 [/itex]  is heavier than [itex]O_2[/itex]. That's why its boiling point is higher than oxygen atoms.

In the [itex] NO_2[/itex] and [itex]CO_2[/itex] pair, the reason for higher boiling point of nitrogen dioxide, is dipole moment of [itex]NO_2[/itex] is 0.32 Debyes whereas that of oxygen, it is 0.
In the  [itex] HF[/itex] and [itex]HCl[/itex] pair, HF has more hydrogen bonding, whereas HCl has dipole-dipole interactions. So, boiling point of HF is higher than that of HCl.

Answer to question 3), In climate with cold winters, water pipes are prone  to breakage due to hydrogen bonding,, thereby resultant water leakages. 

Answer to question 4), Water doesn't overflow in the cup can filled all the way to brim, and then even past the rim, because of surface tension. 

[Babcock_Hall]

Do Van der Waals attractive forces depend on mass or on some other molecular property?

[Win,odd Dhamnekar]

Van der Waals' attractive  forces depend on molecular mass, molecular shape and molecule's 'Polarizability'.

[Babcock_Hall]

When all else is held equal, the London forces depend on surface area.  With respect to water, I would think about density.