Answer:
HF
Explanation:
This concept can be understood from the knowledge of Intermolecular forces of attraction.
Intermolecular bonds are Van der Waals forces which are weak forces of attraction joining non-polar and polar molecules together. They exist in the form of London Dispersion Forces and Dipole-dipole attraction.
An example of Dipole-dipole attraction is the hydrogen bond which is a unique dipole-dipole attraction between polar molecules in which a hydrogen atom is directly joined to a highly electronegative atom such as fluorine, oxygen, or nitrogen).
Molecules that possess the characteristics of hydrogen bonding have a higher boiling point. In the given question, only HF undergo hydrogen bond due to the electronegative effect of the fluorine element.
F2 occurs as a weak London dispersion force and it occurs between non-polar molecules.
Answer:
The molarity of the final solutions if these two solutions are mixed is 27.14 
Explanation:
Yo know:
- Solution-1: 25M, 400mL
- Solution-2: 30M, 300 mL
Molarity being the number of moles of solute per liter of solution, expressed by:

You can determine the number of moles that are mixed from each solution as:
Number of moles= Molarity*Volume
So, being 1 L=1000 mL, for each solution you get:
- Solution-1: being 0.400 L=400 mL ⇒ 25 M* 0.400 L= 10 moles
- Solution-2: being 0.300 L=300 mL ⇒ 30 M* 0.300 L= 9 moles
When mixing both solutions, it is obtained that the volume is the sum of both solutions:
Total volume= volume solution-1 + volume solution-2
and the number of total moles will be the sum of the moles of solution-1 and solution-2:
Total moles= moles of solution-1 + moles of solution-2
So the molarity of the final solution is:

In this case, you have:
- moles of solution-1: 10 moles
- moles of solution-2: 9 moles
- volume solution-1: 0.400 L
- volume solution-2: 0.300 L
Replacing:

Solving:

Molarity= 27.14 
<u><em>The molarity of the final solutions if these two solutions are mixed is 27.14 </em></u>
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Metal usually donates electrons. The concept behind this phenomenon is stability. The elements with the most stable electronic configuration are the noble gases in Group 5A. As a result, the other elements donate or accept electrons so that they would be like the noble gases. Since metals are past their nearest noble gas element, they have to shed their electrons. When they do, they become cations which are positively charged ions.