Answer: The correct answer is the option: B. An element with eight valence electrons is chemically unstable.
Explanation:
Hello! Let's solve this!
We will analyze each of the options:
A. The group number of the element provides a clue to the number of valence electrons: it is correct, since it provides the number of valence electrons.
B. An element with eight valence electrons is chemically unstable: this is not correct, since elements with eight electrons in the valence shell cannot react because they already have the last complete shell. Therefore, they are chemically stable.
C. The points must be placed one at a time on each side of the chemical symbol: it is correct, because that is the way to make the point diagram.
D. An atom is chemically stable if all the points are paired: this is correct since this verifies that the point diagram has been done well.
We conclude that the correct answer is the option: B. An element with eight valence electrons is chemically unstable.
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Answer:
Magnetism is believed to be caused by the alignment of small, numerous sub-units called : <em><u>Domains</u></em>
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Explanation:
Domains : A magnetic domain is the region in which in which magnetic field of the atoms are grouped together and aligned.
- In unmagnetized material all the magnetic Domains point in different direction.
- In magnetised material (ferromagnets , antiferromagnets) , The Domains point in a particular( fixed Pattern) direction.
<em>Answer:</em>
- The atom consist of three parts, proton, neutron and electrons. The electrons determine that i will combine or beak from other substances.
<em>Explanation:</em>
The atom consist of three parts which are following
The proton and neutron form nucleus of an atom. It is present at center of an atom. They have positive charges, while electrons remained outside the nucleus in particular energy levels or shell around the nucleus.
During combination or breaking of substances ,only arrangements of electrons take place. The valence shell electrons decide whether they have to combine or not, while nucleus remained unchanged during any reactions.
Answer:
The statement is true.
Explanation:
Organisms can be unicellular (made up of one cell) or multicellular (consisting of more than one cell).
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Answer:- The pH of the buffer solution will be 4.04 .
Solution:- Sodium acetate added to acetic acid makes a buffer solution and the pH of buffer solution is easily calculated by using Handerson equation:

We are adding 25.00 mL of each, so the total volume of the buffer solution will be 50.00 mL.
We can calculate the concentration of base which is sodium acetate and acid by using dilution equation:


for base:


Similarly, for acid:


pKa is calculated from given Ka value as:


pKa = 4.74
Let's plug in the values in Handerson equation:

pH = 4.74 - 0.70
pH = 4.04