Answer : Any natural sources of CFC's are not known only the major sources like aerosols, propellants, refrigerants,etc are known. So, if any natural sources are given then it cannot be called as a major source for emitting CFC into environment.
Answer:
Ion exchange.
Explanation:
One of the ways in which water can be treated is through the process known as ION EXCHANGE. Using this for treating water has to do basically with the transfer or say the exchange of ions.
Ion exchanges is done by exchanging ions which are considered as 'unfit' or contaminants by the ones that are "fit".
Ions from what is known as zeolite or resin is been exchanged with the ions in the water. Cations are exchanged with cations and anions are exchanged with anions.
NB: this method is a good method or removing contaminants that are ions but not contaminants that are not ions.
Gravity forces earth to move around the sun so A
Explanation:
holes are left due to space left out the migrating electrons. they are positive charge carriers. if the electron moves in one direction, the holes appear to move in the opposite direction.
Answer:
The correct option is the second option
Explanation:
Generally, the aim of science is to understand a particular concept in the best and the most correct way possible; hence experiments are done and repeated to ensure an explanation is actually true about a concept or need modification.
The atomic models have also been a "beneficiary" of this process. The different atomic models are usually been improved upon as scientists leaned more. For example, the Dalton's atomic theory has been modified to a more correct atomic description; some of which are shown below
(1) Dalton's theory suggested that an atom is the smallest unit of a molecule. We know now from different experiments (by J. J Thompson and Rutherford) that atoms are not the smallest molecules and are made up of smaller particles known as protons, neutrons and electrons.
(2) Dalton's theory suggested that atoms of the same elements are alike in all aspects. The knowledge of isotopy shows this is not always the case. As atoms of the same elements (isotopes) have the same atomic number but different mass number; hence cannot be said to be the same in all aspects.
(3) Dalton's theory also suggested that when atoms react, they do so in fixed, simple whole number ratio. The knowledge of organic chemistry shows atoms do not always react in simple whole number ratios
There are several modifications to different postulations by scientists that have also occurred aside from this, hence the most correct answer is that "As scientists learned more, they modified the atomic model"
