Answer:
Object 4 in the example
Explanation:
For simplicity and a clearer view of this problem, let's assume that four masses from 1 to 4 have the the masses 2 kg, 4 kg, 6 kg, 8 kg respectively.
According to the second Newton's law, we know that force is directly proportional to both mass and acceleration. The equation representing this is 
.
Notice that all of them have the same acceleration. This means, the greater the mass, the greater the force for a fixed acceleration. Simply speaking, the forces for each of the objects would be 2a, 4a, 6a and 8a respectively.
Since we're interested in the magnitude of the force and not direction, we neglect whether acceleration is positive or negative. This means that object 4 will require the greatest force to move, as it has the greatest mass.
Plant is complex biological organism which is composed of many organic molecules that fulfill different roles in the plant, some will give the color of the plant, some are "energy reactors" like chlorophyll which capture the photons for promoting certain chemical reactions. Now the organic solvents like acetone and ethyl alcohol do not discriminate between the compounds so the solvent will extract many different molecules from the plant. The extract will be definitely a heterogeneous one.
Using a thin lay chromatography plate you may determine the spots for each organic compound as well as their retention factor for the solvent used as eluent. After concentration the solution, under vacuum, the mixture may be loaded in a chromatography column, previously filled with silica gel as stationary phase. After the elution and collection of each fraction, that contain a different molecule, the plant extract is separated.
Answer:
in physical science, an isolated system is either of the following:
1. a physical system so far removed from other systems that it does not interact with them.
2. a thermodynamic system enclosed by rigid immovable walls through which neither mass nor energy can pass.
Explanation:
Answer: D. New data must be found to support it
When a theory is disproved by other further evidence, it is just proper to look for new data to support the theory until it is proven otherwise. It cannot be considered a failure right away but cannot be part of the scientifi knowledge too and more not to become a law.
