1 mol of Br = 79.9 g
15.7 g / 79.9 g = 0.196 moles of atoms
Answer: Transition from X to Y will have greater energy difference.
Explanation: For studying the energy difference, we require Planck's equation.

where, h = Planck's Constant
c = Speed of light
E = Energy
= Wavelength of particle
From the equation, it is visible that the energy and wavelength follow inverse relation which means that with low wavelength value, energy will be the highest and vice-versa.
As electron A falls from X-energy level to Y-energy level, it releases blue light which has low wavelength value (around 470 nm) which means that it has high energy.
Similarly, Electron B releases red light when it falls from Y-energy level to Z-energy level, which has high wavelength value (around 700 nm), giving it a low energy value.
Energy Difference between X-energy level and Y-energy level will be more.
The strongest of the intermolecular forces are hydrogen bonds
Question is incomplete, complete question is;
A 34.8 mL solution of
(aq) of an unknown concentration was titrated with 0.15 M of NaOH(aq).

If it takes 20.4 mL of NaOH(aq) to reach the equivalence point of the titration, what is the molarity of
? For your answer, only type in the numerical value with two significant figures. Do NOT include the unit.
Answer:
0.044 M is the molarity of
(aq).
Explanation:
The reaction taking place here is in between acid and base which means that it is a neutralization reaction .
To calculate the concentration of acid, we use the equation given by neutralization reaction:

where,
are the n-factor, molarity and volume of acid which is 
are the n-factor, molarity and volume of base which is NaOH.
We are given:

Putting values in above equation, we get:

0.044 M is the molarity of
(aq).