Answer:
Ar 36: Mass number 36, 18 Protons, 18 neutrons and 18 electrons.
Ar 38: Mass number 38, 18 Protons, 20 neutrons and 18 electrons.
Ar 40: Mass number 40, 18 Protons, 22 neutrons and 18 electrons.
Explanation:
The number given after 'Ar' is the mass number.
The atomic number of Argon is 18 which means that 18 protons and 18 electrons are in the atom of Argon. The mass number of an isotope = number of protons + the number of neutrons.
<span>C10H12N2O
First, lookup the atomic weights of C, H, N, and O
Atomic weight of Carbon = 12.0107
Atomic weight of Hydrogen = 1.00794
Atomic weight of Nitrogen = 14.0067
Atomic weight of Oxygen = 15.999
Now determine the ratio of atoms of each element by dividing their mass percentage by their atomic weights.
Carbon = 68.2 / 12.0107 = 5.67827
Hydrogen = 6.86 / 1.00794 = 6.805961
Nitrogen = 15.9 / 14.0067 = 1.135171
Oxygen = 9.08 / 15.999 = 0.567535
Now determine a simple integer ratio of small integers that closely approximates the ratio of relative molar amounts.
5.67827 : 6.805961 : 1.135171 : 0.567535
Going to first divide all values by 0.567535 (picked because it's the smallest in the above ratios) getting
10.005 : 11.992 : 2.000 : 1
These numbers are all extremely close to integers so it looks like the empirical formula for Serotonin is C10H12N2O
Let's compute the molar mass of the empirical formula
10 * 12.0107 + 12 * 1.00794 + 2 * 14.0067 + 15.999 = 176.2 g/mol
Since that calculated molar mass matches the desired target, we're done. If the calculated mass was smaller, or the desired mass was larger (like 352 g/mol) we would have multiplied the number of atoms by the appropriate factor. But that's not needed, so the molecular formula for Serotonin is C10H12N2O</span>
<u>Answer: </u>
Phases of moon:
- New Moon
- crescent Moon
- First-quarter Moon
- gibbous Moon
- full Moon
<u>Explanation:</u>
The lunar cycle has 8 phases. The first phase is new moon. New moon is seen while the moon lies between the sun and the earth. After few days occurs the crescent moon when the moon travels towards its east. The next phase is first-quarter phase. During this phase half of the moon will be illuminated. The fourth phase is waxing gibbous moon phase where waxing refers to 'growing larger' and gibbous means 'shape' hence waxing gibbous refers to growing shape. Next is the full moon phase. This happens when the moon and the sun comes on the opposite sides of our earth. The next phase will be waning gibbous moon where the moon decreases in size. This phase is followed by third quarter and finally the waning crescent moon phase.