Answer: Option (D) is the correct answer.
Explanation:
- A pure substance is defined as the substance that is made up of only one type of atom or only one type of molecule.
For example, 
is a molecule and it is a pure substance.
Also, substances that contain two or more different element which are chemically combined in a fixed ratio by mass are known as compounds. They are also pure substances.
A pure substance can only be separated by a chemical method and not by any physical method.
- A heterogeneous mixture is defined as the mixture which contains non-uniform composition of solute particles into the solution.
For example, mud dissolved in water.
It is not necessary that two or more substance present in a heterogeneous mixture should be of same phase.
Also, it is not necessary that combination of a liquid and a solid always results in a heterogeneous mixture.
If the solid is able to dissolve completely into the liquid then it will result in a homogeneous mixture.
- Whereas a homogeneous mixture is defined as the mixture which contains uniform distribution of solute particles into the solvent.
For example, salt dissolved in water is a homogeneous mixture.
Thus, we can conclude that the statement composition is uniform throughout a homogeneous mixture, is correct.
Answer:
Thomson placed two magnets on either side of the tube, and observed that this magnetic field also deflected the cathode ray. The results of these experiments helped Thomson determine the mass-to-charge ratio of the cathode ray particles, which led to a fascinating discovery, minus the mass of each particle was much, much smaller than that of any known atom. Thomson repeated his experiments using different metals as electrode materials, and found that the properties of the cathode ray remained constant no matter what cathode material they originated from. From this evidence, Thomson made the following conclusions:
The cathode ray is composed of negatively-charged particles.
The particles must exist as part of the atom, since the mass of each particle is only ~1/2000 the mass of a hydrogen atom.
These subatomic particles can be found within atoms of all elements.
While controversial at first, Thomson's discoveries were gradually accepted by scientists. Eventually, his cathode ray particles were given a more familiar name: electrons. The discovery of the electron disproved the part of Dalton's atomic theory that assumed atoms were indivisible. In order to account for the existence of the electrons, an entirely new atomic model was needed.
Explanation:
The gases that get released form bubbles in the solution
