a) The E might belong to group 13.
As the formula of a chemical compound is derived by the cross multiplication of the valency of the atoms. As formula of the given oxide is and valency of O atom is -2, therefore valency of element E must be +3 in order to obtain E2O3.
Also, in EF3, the valency of E will be +3 because there are three atoms of fluorine who has an individual valency of -1. Thus, e will have the valency of +3.
The Group 13 is the boron group which has the following elements:
- Boron
- Aluminium
- Gallium
- Indium
- Thallium
All these elements have the valency of +3.
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Answer: energy=mgh 55*9.8*10.8= 5821.2 J <--- this can't be wrong, there's no other way to solve for it. set the potential energy equal to kinetic energy: 5821.2= 1/2...
During change of phase, the molecules of a substance acquire enough kinetic energy to overcome the forces of attraction between its molecules.
<h3>What is change of phase?</h3>
Change of phase occurs when a substance acquires enough energy to overcome the forces of attraction between its molecules to transition from one state of matter to another.
During a change of phase, kinetic energy of the molecules of the substance increases due to the application of heat, and the freedom of movement of the molecules increases.
Change of phase can occur as follows;
- from solid to liquid and vice versa
- from solid to gas and vice versa
- from liquid to gas and vice versa
Therefore, during change of phase, the molecules of a substance acquires enough kinetic energy to overcome the forces of attraction between its molecules leading to increased freedom of movement of the molecules.
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We have that the statement of Bohr's model understanding of electron energy levels is True
Option A
<h3>Electron energy levels</h3>
Generally, Bohr's model in his famous publication saw to explaining where <em>electrons</em> could be found. The model also explains the properties of different elements.
Therefore, The statement "A major advancement of from the Bohr model of the atom was the understanding of electron energy levels." is
True
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