Answer:

Given:
1$ = 4q
To Find:
How many quarters are in 20$
Explanation:
To find out how many quarters are in 20$ we need to multiple 4 × 20.



Your answer should be D
let me know if I got it wrong
Hope this helped!
Answer:
The correct option is;
B. Designing experiments to replicate the conditions in which life may have first evolved on Earth
Explanation:
The proof to the hypothesis that life originated from inanimate inorganic, or non-living molecules which is an explanation for the origin of life on Earth was provided by an experiment designed and performed in 1953 by Stanley L. Miller and Harold C. Urey which consisted of using chemicals proposed in the hypothesis and combining them through a specific design process to replicate expected atmospheric condition before the life began on Earth.
With such successful design of experiments to replicate the conditions in which life may have first evolved on Earth, it was possible to better explain the hypothesis that life originated from inorganic molecule.
Answer : The energy of one photon of hydrogen atom is, 
Explanation :
First we have to calculate the wavelength of hydrogen atom.
Using Rydberg's Equation:

Where,
= Wavelength of radiation
= Rydberg's Constant = 10973731.6 m⁻¹
= Higher energy level = 3
= Lower energy level = 2
Putting the values, in above equation, we get:


Now we have to calculate the energy.

where,
h = Planck's constant = 
c = speed of light = 
= wavelength = 
Putting the values, in this formula, we get:


Therefore, the energy of one photon of hydrogen atom is, 