Noble gases
Explanation:
Electronic configuration 1s² 2s² 2p⁶
The element belongs to the group of the noble gases.
- The noble gases have complete outer shell configuration of their atoms.
- we can infer that the configuration above is for an element in the p-block because the last sub-level filled is the p-orbital.
- The elements therefore belongs to the p-block
- The block is from group 111A to O
- Only the halogens and noble gases fits this picture from the option.
- The outer most p-subshell have three orbitals requiring 6 electrons to fill them up.
- This makes a complete and stable configuration.
- The highest energy level of 2 is also made up of 8 electrons, an octet.
- This is why we can conclude that they are noble gases.
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Noble gas brainly.com/question/1781595
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Answer is: a) in the presence of a base.
Phenolphthalein is colorless in acidic solutions and pink in basic solutions.
Acid-base indicators are usually weak acids or bases and they are chemical detectors for hydrogen or hydronium cations.
Example for acid-base indicator is phenolphthalein (molecular formula C₂₀H₁₄O₄).
When solution turns phenolphthalein pink, it means it is basic (pH>7).
To Find :
The volume of 12.1 moles hydrogen at STP.
Solution :
We know at STP, 1 mole of gas any gas occupy a volume of 22.4 L.
Let, volume of 12.1 moles of hydrogen is x.
So, x = 22.4 × 12.1 L
x = 271.04 L
Therefore, the volume of hydrogen gas at STP is 271.04 L.
I don’t know about 1 But number 2 is AB + xH2O = AB.xH2O
