"The other halogens are not as electronegative and so other hydrogen halides cannot form hydrogen bonds between molecules. Only London Forces are formed. - Therefore more energy is required to break the intermolecular forces in HF than the other hydrogen halides and so it has a higher boiling point."
not a hack link, just stating where i got your answer from! -
https://www.mytutor.co.uk/answers/17558/A-Level/Chemistry/Explain-the-unusually-high-boiling-point-of-HF/
Answer: Option (B) is the correct answer.
Explanation:
Expression for the given decomposition reaction is as follows.

Let us assume that x concentration of
is present at the initial stage. Therefore, according to the ICE table,

Initial : x 0
Change : - 0.1 
Equilibrium : (x - 0.1) 0.2
Now, expression for
of this reaction is as follows.

Putting the given values into the above formula as follows.



x = 0.12
This means that
= x = 0.12 atm.
Thus, we can conclude that the initial pressure in the container prior to decomposition is 0.12 atm.
Hey!!
here is your answer >>>
In order to find out which metal gains heat faster, we will have to find out their specific heat!. Specific heat is the heat required to raise the temperature of the unit substance, The specific heat of gold and brass are 0.126 for gold and 0.380 for brass!. The specific heat of gold is less than brass!. So, gold will gain heat faster!.
Hope my answer helps!