In the physical properties, it is mentioned that the element has 4 valence electrons. The elements in the periodic table are arranged such that, the number of valence electrons present in the neutral atoms belonging to a particular group is equal to the group number.
Thus, the unidentified element can be best classified as a nonmetal in period 4
Ans C)
Answer:
OPTION C) All hydrogen ions and all hydroxide ions have reacted to produce water, and so neither ion remains free in solution.
Explanation:
The PH reading on the left axis of the graph shows a value of 7.
A value of 7 on the PH scale implies that equal number of hydrogen ions completely reacted with hydroxyl ions to produce water i.e there is no excess of hydrogen and hydroxyl ion remaining in solution.
For values greater than 7, a basic solution is formed and it signifies the presence of excess hydroxyl ion. If the value is less than 7, there is more hydrogen ions in the solution formed and it is said to be acidic.
At point 7, the hydrogen and hydroxyl ions are equal and completely neutralize out one another.
Note: The acid solution would require a base volume of 20mL to be completely neutralized according to the plot. If it is less, the PH shifts to the left and the solution becomes acidic. If it more, the solution becomes basic and the PH shifts rightwards.
Answer: The correct option is (c). The total pressure doubles.
Solution:
Initially, only 4 moles of oxygen gas were present in the flask.
(
) ( according to Dalton's law of partial pressure)
....(1)
= Total pressure when only oxygen gas was present.
Final total pressure when 4 moles of helium gas were added:
partial pressure of oxygen in the mixture :
Since, the number of moles of oxygen remains the same, the partial pressure of oxygen will also remain the same in the mixture.
= Total pressure of the mixture.
from (1)
On rearranging, we get:
The new total pressure will be twice of initial total pressure.
