The model would look something like the image below.
There would be a <em>central nucleus</em> containing <em>20 protons</em> and <em>20 neutrons</em>.
Surrounding the nucleus would be four concentric rings (energy levels) containing <em>20 electron</em>s.
Going out from the nucleus, the number of electrons in each ring would
be <em>2, 8, 8, 2</em>.
<span>pm stands for picometer and picometers are units which can be used to measure really tiny distances. One picometer is equal to 10^{-12} meters. We know that one centimeter is equal to 10^{-2} m so there are 10^2 cm per meter.
We can change the distance d = 115 pm to units of centimeters.
d = (115 pm) x (10^{-12}m / pm) x (10^2 cm / m)
d = 115 x 10^{-10} cm = 1.15 x 10^{-8} cm
The distance in centimeters is 1.15 x 10^{-8} cm</span>
<u>Answer:</u> The mass percent of hydrogen in methyl acetate is 8 %
<u>Explanation:</u>
The given chemical formula of methyl acetate is 
To calculate the mass percentage of hydrogen in methyl acetate, we use the equation:

Mass of hydrogen = (6 × 1) = 6 g
Mass of methyl acetate = [(3 × 12) + (6 × 1) + (2 × 16)] = 74 g
Putting values in above equation, we get:

Hence, the mass percent of hydrogen in methyl acetate is 8 %
Answer:
Explanation:
In one of the process, energy is built up from scratch, in the other one, energy is liberated for use by an organism or body.
The first process deals with a metabolic reaction in which energy is liberated:
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy
In the above process, energy is liberated when glucose combines with oxygen. The waste products are carbon dioxide and water. This process liberates heat energy which can be used to do work.
In the reverse process:
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
This process stores energy in carbon chains as chemical energy. It is this energy that is released in the first process.
Therefore, we can see that the first process liberates energy and the reverse process stores energy.
Answer:
1 and 3.
Explanation:
The entropy measures the randomness of the system, as higher is it, as higher is the entropy. The randomness is associated with the movement and the arrangement of the molecules. Thus, if the molecules are moving faster and are more disorganized, the randomness is greater.
So, the entropy (S) of the phases increases by:
S solid < S liquid < S gases.
1. The substance is going from solid to gas, thus the entropy is increasing.
2. The substance is going from a disorganized way (the molecules of I are disorganized) to an organized way (the molecules join together to form I2), thus the entropy is decreasing.
3. The molecules go from an organized way (the atom are joined together) to a disorganized way, thus the entropy increases.
4. The ions are disorganized and react to form a more organized molecule, thus the entropy decreases.