Answer : The energy released by an electron in a mercury atom to produce a photon of this light must be, 
Explanation : Given,
Wavelength = 
conversion used : 
Formula used :

As, 
So, 
where,
= frequency
h = Planck's constant = 
= wavelength = 
c = speed of light = 
Now put all the given values in the above formula, we get:


Therefore, the energy released by an electron in a mercury atom to produce a photon of this light must be, 
Answer:
The mole fraction of ethanol is 0.6. A 10 mL volumetric pipette must be used for to measure the 10 mL of ethanol. The vessel should be clean and purged.
Explanation:
For calculating mole fraction of ethanol, the amount of moles ethanol must be calculated. Using ethanol density (0.778 g/mL), 10 mL of ethanol equals to 7.89 g of ethanol and in turn 0.17 moles of ethanol. The same way for calculate the amount of water moles (ethanol density=0.997 g/mL). 2 mL of water correspond to 0.11. The total moles are: 0.17+0.11=0.28. Mole fraction alcohol is: 0.17/0.28=0.6
I would assume so.
Given

, we can simplify the fraction to

Both would obtain the same proportions, so I don't see why putting a half cup of sugar would make things any different.
Hope this is the answer you are looking for.
Chemistry. More specifically, analytical chemistry.