Answer:
If the discs floated, they produced oxygen and gained buoyancy.
Answer:
The car is carrying a volume of air that is moving at 80 mph relative to the ground. But inside the car itself, the air not moving very much. If you take the windshield out and drive a 80 mph you will smash the fly onto the back window.
Explanation:
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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
The fourth one: Gain of an electron
12.5%
Three half lives pass. 50% -> 25% -> 12.5%