This is the only option that correctly describe characterisitics of noble gases.
All noble gases have a unique atomic fingerprint.
All noble gases have valence shells with 8 electrons but Heilum has only 2 valence electrons.
And all noble gases do not easily react with other elements as they have their outermost shell completly filled so they are highly stable.
All noble gases emits different colored light when electrified.
Answer: There are several ways. The first that comes to mind is a pH meter. A pH electrode Is lowered into the solution, and (Assuming) the pH Meter has been properly calibrated, and the temperature of the solution is set to the calibration of the Meter, the pH can be read directly from an analogue scale or digital readout. Below 7 is acidic, 7 is Neutral, (like Pure Water), and over 7 is Alkaline, or Basic.
A useful, but less accurate method is the use of any number of “pH Indicator Solutions”, which are essentially a type of various colored dyes that change color within differing pH ranges. Usually, if the pH is unknown, a small amount of solution is removed from the container and tested separately - in a “well plate”, or similar method.
These types of dyes, or Indicator Solutions, can be dried upon strips of “pH indicator Paper”, which, depending upon the type can be very useful when carrying out more precisely arrived at pH tests like Titration.
Just to see if a solution is “Acid” or “Base”, Litmus paper is used; “a Red color shows Acidity, and a Blue color, a Base”; ergo, “An Acid Solution will turn Litmus Paper, Red”.
Answer : The correct option is, (c) 79.62
Explanation :
The formula used for percent humidity is:
..........(1)
The formula used for relative humidity is:
...........(2)
where,
= partial pressure of water vapor
= vapor pressure of water
p = total pressure
First we have to calculate the partial pressure of water vapor by using equation 2.
Given:


Relative humidity = 80 % = 0.80
Now put all the given values in equation 2, we get:


Now we have to calculate the percent humidity by using equation 1.


Therefore, the percent humidity is 79.62 %
Grams of Phosphorus = 4.14 grams
Grams of white compound = 27.8 grams
Grams of Chlorine would be = 27.8 - 4.14 = 23.66 grams
Calculating moles which would be grams / molar mass
Molar mass of P = 30.97 grams / moles; Molar mass of Cl = 35.45 grams / moles
Moles of Phosphorus = 4.14 grams / 30.97 grams / moles = 0.1337 moles
Moles of Chlorine = 23.66 grams / 35.45 grams / moles = 0.6674 moles
Calculating the ratios by dividing with the small entity
P = 0.1337 moles / 0.1337 moles = 1
Cl = 0.6674 moles / 0.1337 moles = 5
So the empirical formula would be PCl5