The correct answer would be the last one.
Answer:

Explanation:
A covalent bond involves the sharing of electrons to make the atoms more stable, and so they satisfy the Octet Rule (8 valence electrons).
Typically each atom contributes an electron to form an electron pair. This is a single bond. There are also double bonds (two pairs of electrons), triple bonds (three pairs of electrons), and coordinate covalent bonds.
Sometimes, to satisfy the Octet Rule and achieve stability, one atom contributes both of the electrons in an electron pair. This is different from other covalent bonds because usually each of the 2 atoms contributes an electron to make a pair.
C- more than one light year or B-exactly one light year
Answer:
398 mL
Explanation:
Using the equation for molarity,
C₁V₁ = C₂V₂ where C₁ = concentration before adding water = 8.61 mol/L and V₁ = volume before adding water, C₂ = concentration after adding water = 1.75 mol/L and V₂ = volume after adding water = 500 mL = 0.5 L
V₂ = V₁ + V' where V' = volume of water added.
So, From C₁V₁ = C₂V₂
V₁ = C₂V₂/C₁
= 1.75 mol/L × 0.5 L ÷ 8.61 mol/L
= 0.875 mol/8.61 mol/L
= 0.102 L
So, V₂ = V₁ + V'
0.5 L = 0.102 L + V'
V' = 0.5 L - 0.102 L
= 0.398 L
= 398 mL
So, we need to add 398 mL of water to the nitric solution.
Answer:
Heat transfer in step 2 = 47.75 J
Explanation:
Internal energy = heat + work done
U = Q + W
In a cyclic process the total internal energy change of the system = 0.
In the process there are two steps. The total heat exchange in the process is the sum of heat exchanges in the two processes.
We have to find the heat exchange in step 2.
In step 1,
W = 1.25 J Q = -37 J
= -37 + 1.25 = -35.75 J
In step 2, the internal energy change will be negative of that in step 1.
U = 35.75 J
W = -12 J
U = Q + W
35.75 = Q -12
Q = 47.75 J
Heat transfer in step 2 = 47.75 J