Chemistry test
English
Intermediate
30
Questions
5 min
Per question
32:33
Average time
3.0
Contest Score
27
Participants
4 comments
Smart Tiger judge
1. Basic Explanations. Explanations expand the correct answer.
Cool Deer
Great quiz! But in a question "Which of the following statements is false?" the right option assigned is "disorderliness increases from solid to gas". Isn't that a true statement? Because entropy increases from solid to gas.
Happy Chameleon
I think there are some mistakes:
Question 9: you said that in thiosulphate ion one of the sulphur atom has an oxydation state of +4 and the other one has 0 oxydation state because it does not carry electrical charge. This is not true.
First of all the absence of electrical charge does not mean it have 0 oxydation state.
Actually the central sulphur atom has an oxydation state of +6 while the one that substitutes the oxygen atom has the same oxydation state that would have had the oxygen atom that is -2.
https://en.m.wikipedia.org/wiki/Thiosulfate

Question 18: you selected as the right answer "disorderliness increases from solid to gas" but in the explanation you contradict yourself since you say that "The entropy of gases is greater than that of solids". And in fact that statement is true and it can not be the right answer since you asked for the false one.
The right answer that is the false statement is "randomness decreases from solid to gas". It is true the opposite.

Question 20: if you want to give the right answer you should have said that "the chemical equilibrium is established when...the rate of formation of the products starting from the reagents is the same of the rate of formation of the reagents starting from the products".
If you say that "the chemical equilibrium is established when...concentration of the reactants and products remain unchanged" looks like the equilibrium is static: once you created the products from the reagets you are done and molecules remains as they are; reagents remain reagents and products remain products.
This is not true. The chemical equilibrium is not static but dinamic. That means that after you have reached the equilibrium, continuously, reagents are still converted into products and products are still converted into reagents.
Slim Horse author
The oxidation state of Sulphur in thiosuplhate ion has three variance which are -1 & +5, 0 & +4 and -2 & +6. There is generally no shift of electron between two atoms of the same element. So no shift of electron between the two sulphur atoms. Thus, the side sulphur cannot have a charge in the rule of counting electrons. Each of the oxygen atoms give oxidation state of -2 which is a total of -6, since the net charge on the ion is -2 then the oxidation state of the central sulphur should be +4.

Question 18 is an oversight on my part. I saw this competition about 3hours to the deadline.

Question 20. I do not have problem with it

Thanks for your observations
Take the quiz to leave a comment