Answer: C the study of living things
Explanation:
The answer is the periodic table it holds about 107 elements that are written on it
Answer:
Transition from n = 4 to n = 1 corresponds to shortest wavelength.
Explanation:
Process 
A 0.9375
B 0.75
C 0.0421
D 0.1875
According to Rydberg equation for electronic transition in H-like atoms:

where,
is wavelength of light emitted or absorbed,
is Rydberg constant.
So, higher the value of
, lower will the corresponding wavelength of light.
Hence process A will be associated with shortest wavelength.
Answer:
Gravity
Explanation:
An object's weight is dependent on its mass and how strongly gravity pulls on it. The strength of gravity depends on how far away one object is from another. That's why the same object weighs different amounts on different planets.