Helium has two valence electrons, and these electrons sre located in the 1s subshell. Without using the periodic table, in which
2 answers:
Answer: Option (A) is the correct answer.
Explanation:
Atomic number of helium is 2 and its electronic configuration is . As here n = 1 this means that helium element belongs to period 1.
Since, helium atom has completely filled s-shell this means that it is unreactive in nature as it neither needs to lose or gain an electron in order to attain stability.
And, all the unreactive elements in the periodic table belongs to group 8A. That is why, helium also belongs to group 8A and period 1.
Thus, we can conclude that helium is located in Group 8A, Period 1 .
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You'll need to react 7,5 moles of Sodium with sulfuric acid to produce 3.75 moles of sodium sulfate
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First of all, you need to balance the reaction. The balanced reaction is shown below (ensuring that the Law of Conservation of Mass is met on both sides):
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Now, all that you have to do is to use molar equivalences in this reaction applying the coefficients to calculate the moles of Sodium that you'll need:
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