In the dark waters just below the photic zone, because of cellular respiration, the concentration of dissolved carbon dioxide is higher relative to dissolved oxygen.
In cellular respiration living organisms use oxygen and release carbon dioxide, because there is little or no light there is no photosynthesis and oxygen is little produced.
Copper + sulfur create copper sulfide.
It's a lengthy process to find the empirical formula:
Sulfur:

Copper:

S:Cu =>
=>
=> 
The empirical formula would just be 
Answer:
A mixed fraction is a fraction composed of a whole number and a fraction such as 2⅔
Answer : The reaction rate at
are 
Solution : Given,
Mass of tablet = 1000 mg
Volume of water = 0.200 L
The given formula will be,

Now we have to calculate the reaction rate at different temperatures and reaction time.




Therefore, the reaction rate at
are 
Any substance changes to another substance that means the change of the physical property. Like water (
) has different state which changes as the temperature changes. It remain as liquid in the room temperature, in solid form at or below 0°C and vapor phase on or above 100°C. But in all the stage or phase of the substance the composition of the water i.e.
remains. Thus the chemical property remains fixed when a substance change to other substance.