Answer: The correct answer is the option: B. An element with eight valence electrons is chemically unstable.
Explanation:
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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:
ΔU = −55.45 kJ
Explanation:
From first law of thermodynamics in chemistry, we have;
ΔU = Q + W
where;
ΔU is change in internal energy
Q is the net heat transfer
W is the net work done
We are given;
Q = 74.6 kJ
But Q will be negative since heat is released
Thus;
ΔU = -74.6 kJ + W
We are given;
Constant pressure; P = 35 atm = 35 × 101325 = 3546375 N/m²
Volume before reaction; Vi = 8.2 L = 0.0082 m³
Volume after reaction; V_f = 2.8 L = 0.0028 m³
Now,
W = -P(V_f - V_i)
W = - 3546375(0.0028 - 0.0082)
W = 19.15 KJ
Thus;
ΔU = Q + W
ΔU = -74.6 kJ + 19.15 KJ =
ΔU = −55.45 kJ
Answer;
A scalene
Explanation;
A triangle is a geometric figure with three sides and three angles that always add up to 180 degrees.
Based on properties triangles can be classified as equilateral, scalene, isosceles and right triangles.
Equilateral triangles has all the three sides and the angles equal, an isosceles triangle has two of its sides equal, and two angles that are known as the base angles equal. A scalene triangle has all the three angles and sides different from each other. A right triangle is a triangle in which one of the angle is right angle or is 90 degrees.
An isosceles triangle may be a right triangle, equilateral triangle, and also may be an acute triangle, however an isosceles triangle can never be a scalene triangle
1. Make an observation
: My toaster doesn't toast my bread
2. Ask a question
: Why doesn't my toaster work?
3. Form a hypothesis
: My coffeemaker works when plugged into the outlet
4. Make a prediction
: If something is wrong with the outlet, then my coffeemaker also won't work when plugged into it
5. Conduct an experiment
: I plug my coffeemaker into the outlet
6. Analyze the results
: There is something wrong with the electrical outlet
Explanation:
The solution to the problem is as shown above.
- A scientific method follow a methodical way of critically carrying out an inquiry into an observation.
- Firstly, an observation is usually made with our senses. Here the researcher observes that the toaster does not toast his bread probably after a long wait.
- He then proceeds to ask why the toaster does not work.
- To investigate this, the forms a hypothesis. A hypothesis is a scientific guess. It is a tentative proposition about an investigation.
- The researcher then makes a prediction about the outlet that might be faulty.
- With this background, he goes on to carry out an experiment to substantiate his findings. This is seen when he plugs the coffeemaker into the outlet.
- From the analysis of result, he sees that that something is wrong with the outlet.
Learn more:
purpose of experiment brainly.com/question/5096428
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