I think answer is
C. Something that can be observed or measured while changing the identity of the substance
<u>Answer:</u> The number of molecules of carbon dioxide gas are 
<u>Explanation:</u>
To calculate the molar solubility, we use the equation given by Henry's law, which is:

where,
= Henry's constant = 
= molar solubility of carbon dioxide gas
= pressure of carbon dioxide gas = 0.250 atm
Putting values in above equation, we get:

To calculate the number of moles for given molarity, we use the equation:

Molarity of carbon dioxide = 
Volume of solution = 0.550 L
Putting values in above equation, we get:

According to mole concept:
1 mole of a compound contains
number of molecules
So,
moles of carbon dioxide will contain =
number of molecules
Hence, the number of molecules of carbon dioxide gas are 
I believe Erosion is the process most likely responsible for the removal of the missing parts of the rock layers. Erosion involves the physical action of surface processes that removes soil, rock, or dissolved material from one location on the Earth's crust, then moved away to another location.
Answer:
Solid:- Particles vibrate in a rigid structure and do not move relative to their neighbors.
Liquid:- It takes the shape of its container but keeps a constant volume.
Gas:- Particles move rapidly and independently of each other.
Plasma:- It is the most common state of matter in the universe.
Explanation:
Solids are one of the three states of matter and, unlike liquids or gases, they have a definite shape that is not easy to change. Different solids have particular properties such as stretch, STRENGTH, or hardness that make them useful for different jobs.
A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure
Gas is a state of matter that has no fixed shape and no fixed volume. Gases have lower density than other states of matter, such as solids and liquids. When more gas particles enter a container, there is less space for the particles to spread out, and they become compressed. The particles exert more force on the interior volume of the container.
A plasma is a gas that has been energized to the point that some of the electrons break free from, but travel with, their nucleus.