Answer: 8.2
Explanation:
pH of a solution is - Log [ H+].
pH = - Log [ 6.2 x 10-9 M]
= 9 - 0.7924
pH = 8.24 approx 8.2
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.
Answer : The number of moles of
produced will be, 0.241 moles.
Solution : Given,
Mass of Fe = 27.0 g
Molar mass of
= 56 g/mole
First we have to calculate the moles of
.

Now we have to calculate the moles of 
The balanced chemical reaction is,

From the reaction, we conclude that
As, 4 mole of
react to give 2 mole of 
So, 0.482 moles of
react to give
moles of 
Thus, the number of moles of
produced will be, 0.241 moles.
There are many properties to substances.
I'll list some examples below:
- Mass
- Volume
- Density
- Conductivity
- Malleability
- Boiling point
- Melting point
- Heat capacity
Hope this helps! :3
Answer:
C. The Speed of the ball depends on the force used to kick it.
Explanation: