Answer:
A
both forms of energy referred to in the question is light and heat energy
light energy is the visible energy that travels at a known constant speed of 3.0×10^9m/s
while heat energy is the invisible energy that travels in form of radiation at variable speeds
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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The Law of Conservation of Mass states that the mass of reactants entering a reaction must be equal to the mass of the products exiting it. In this case, we only have 2 reactants, Fe and S, and we only have 1 product, FeS. Therefore we expect the total mass of the Fe and S reactants to equal the mass of FeS. This gives us 112 g + 64 g = 176 g of FeS, which is choice D.
Answer:
A3+ and B-
Explanation:
Elements in group 13 have outermost electron configuration, ns2np1 hence they form trivalent positive ions.
Elements in group 17 have outermost electron configuration ns2np5 hence they form univalent negative ions.
This implies that, if element A is in Group 13 and element B is in Group 17, the ions formed are A3+ and B-.
