F = ma
500 = m x 15
m = 33.33 kg
All black surfaces is the correct answer
Answer:

Explanation:
The Hi line of the Balmer series is emitted in the transition from n = 3 to n = 2 i.e.
and 
The wavelength of Hi line of the Balmer series is given by :




So, the wavelength for this line is 550 nm. Hence, this is the required solution.
<span>Which of the following is the correct unit for time when calculating power in watts?
</span>
The correct unit for time when calculating power in watts is seconds. The answer is letter D. The rest of the choices do not answer the question above.