To know the density you also need to know the volume of the rock.
Answer:
It will a because it has a lower density than water
It states the fact, which we now know, that electrons are responsible for the chemical bonding. According to this theory, valency is the number of electrons present in the outermost energy shell of the atom. This energy shell is called valency shell.
Complete Question
The complete question is shown on the first uploaded image
Answer:
The concentration of
that should used originally is 
Explanation:
From the question we are told that
The necessary elementary step is

The time taken for sixth of 0.5 M of reactant to react 
The time available is 
The desired concentration to remain
Let Z be the reactant , Y be the first product and X the second product
Generally the elementary rate law is mathematically as

Where k is the rate constant ,
is the concentration of Z
From the elementary rate law we see that the reaction is second order (This because the concentration of the reactant is raised to power 2 )
For second order reaction

Where
is the initial concentration of Z which a value of 
From the question we are told that it take 9 hours for the concentration of the reactant to become


So


=> 
For 





Answer: well i guess we can say that is a scale used to specify the acidity or basicity of an aqueous solution and it is important to keep ph of hot tub water between 7 and 7.6 because if it is not balanced the water can negatively affect your tub.
Explanation:
pH is an extremely important chemical level to maintain in your spa's water chemistry. A high pH or a low pH will spell trouble for you and your spa. On the pH scale, a reading of 7.4-7.6 indicates perfectly balanced pH. Any number lower than 7.4 means that your water is now considered “acidic”.