C. 6 Valence electrons. Remember that the family that they are in will determine the number of valence electrons that element will have. Sulfur is in family 16 so it will have 6 Valence electrons.
Explanation: Hydrogen bonds are the strongest one of the intermolecular forces. A hydrogen bond is a bond between hydrogen in one molecule or the other ones are fluorine and nitrogen. So it's between a hydrogen in one molecule and an electronegative atom in another molecule. So they always involve hydrogen.
Can vary. Carbon is used quite commonly, and extracts metal oxides, works with zinc, iron, tin, lead and copper.
Explanation:
The given data is as follows.
Volume of lake =
= 
Concentration of lake = 5.6 mg/l
Total amount of pollutant present in lake = 
=
mg
=
kg
Flow rate of river is 50 
Volume of water in 1 day = 
=
liter
Concentration of river is calculated as 5.6 mg/l. Total amount of pollutants present in the lake are
or 
Flow rate of sewage = 
Volume of sewage water in 1 day =
liter
Concentration of sewage = 300 mg/L
Total amount of pollutants =
or 
Therefore, total concentration of lake after 1 day = 
= 6.8078 mg/l
= 0.2 per day
= 6.8078
Hence,
= 
=
= 1.234 mg/l
Hence, the remaining concentration = (6.8078 - 1.234) mg/l
= 5.6 mg/l
Thus, we can conclude that concentration leaving the lake one day after the pollutant is added is 5.6 mg/l.