<span>Thermal energy is often referred to as heat energy.</span>
Answer: Wavelength associated with the fifth line is 397 nm
Explanation:

= Wavelength of radiation
E= energy
For fifth line in the H atom spectrum in the balmer series will be from n= 2 to n=7.
Using Rydberg's Equation:

Where,
= Wavelength of radiation
= Rydberg's Constant =
= Higher energy level = 7
= Lower energy level = 2 (Balmer series)
Putting the values, in above equation, we get



Thus wavelength λ associated with the fifth line is 397 nm
1st and 4th options are suitable answers, as these 2 changes are not exactly physical changes as it cant return back to original form and as well as its not cooling, so I feel its 1st and 4th options
I believe it the answer is 3412
Answer: Number of protons and number of valance electrons.
Explanation:
There are three factors which determine metallic bond strength. greater the no of protons, greater will be attraction between nucleus and valance shell electrons and stronger will be metallic bond. greater no of valance electron, greater will be attractions between nucleus and electrons and stronger will be bond.