Answer:
See the images below
Step-by-step explanation:
To draw a dot diagram of an atom, you locate the element in the Periodic Table and figure out how many valence electrons it has. Then you distribute the electrons as dots around the atom,
a. Silicon.
Si is in Group 14, so it has four valence electrons.
b. Xenon
Xenon is in Group 18, so it has eight valence electrons. We group them as four pairs around the xenon atom.
c. Calcium
Calcium is in Group 2, so it has two valence electrons. They are in a single subshell, so we write them as a pair on the calcium atom.
d. Water
Oxygen is in Group 16, so it has six valence electrons. The hydrogen atoms each contribute one electron, so there are eight valence electrons.
Chemists often use a dash to represent a pair of electrons in a bond.
Answer:

Explanation:
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Unfortunately, the question is not given in the question; however, it is possible for us to compute the equilibrium constant as the problem is providing the concentrations at equilibrium. Thus, we first set up the equilibrium expression as products/reactants:
![K=\frac{[NO_2]^2}{[NO]^2[O_2]}](https://tex.z-dn.net/?f=K%3D%5Cfrac%7B%5BNO_2%5D%5E2%7D%7B%5BNO%5D%5E2%5BO_2%5D%7D)
Then, we plug in the concentrations at equilibrium to obtain the equilibrium constant as follows:

In addition, we can infer this is a reaction that predominantly tends to the product (NO2) as K>>>>1.
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Answer:
D
Explanation:
D. The number of moles of a dissolved substance
Answer:
a. Earth casts a shadow on the moon.
Explanation:
Lunar eclipse occurs when Earth comes in between sun and moon. The sunlight falling on moon is blocked by Earth and the shadow of earth falls on moon. This happens on full moon day when sun, earth and moon align in one line.The moon passes through the shadow of earth and appears dark.
Thus, the correct option is a.
<h3>The ozone layer acts as a shield for life on Earth. Ozone is good at trapping a type of radiation called ultraviolet radiation, or UV light, which can penetrate organisms' protective layers, like skin, damaging DNA molecules in plants and animals.</h3>
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