What must be part of a quantitative observation?
a change of state
a change in size
a number
a color

a number

Explanation:

Quantitative observation is taking any kind of measurement using a tool like measuring the volume of water or weighing the mass of a metal.  

Qualitative observation is just a physical observation with no measurements involved.

1. Change of state is a qualitative observation. There is no measurement involved.  

2.  Change in size is a qualitative observation. There is no measurement involved.  

3. A number is involved in a qualitative observation. Example: Measurement of length as 10 m.

4. Color is a qualitative observation. There is no measurement involved.  

the answer is:  

line graphs show patterns in data with variables that change over time; whereas, circle graphs show data as parts out of a whole (such as out of 100%).

consider the reaction below.

 no rx

at 500 k, the reaction is at equilibrium with the following concentrations.

[pci5]= 0.0095 m

[pci3] = 0.020

[ci2] = 0.020 m

what is the equilibrium constant for the given reaction?

0.042

0.42

2.4

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