The density of marble is between 2.6 and 2.8 grams per cm³ .
Density doesn't depend on how much mass or volume of it you have.
The density of a chip of it is the same as the density of a truckload of it.
<u>Answer:</u> The volume of HBr solution required is 130.16 mL
<u>Explanation:</u>
To calculate the concentration of base, we use the equation given by neutralization reaction:

where,
are the n-factor, molarity and volume of acid which is 
are the n-factor, molarity and volume of base which is 
We are given:

Putting values in above equation, we get:

Hence, the volume of KOH solution required is 130.16 mL
Answer:
Know this
1mole of a substance contains 6.022x10²³molecules
Now
8.55x10^-15moles x 6.022x10²³molecules/1mole
=5.15x10^9molecules.