The atomic mass of potassium is 19 g/mol
90.0 g of potassium contains ;
= 90.0/19
= 4.737 moles
The reaction between potassium and nitrogen is given by the equation;
6K + N2 = 2K3N
The mole ratio of potassium and nitrogen is 6:1
The number of moles of nitrogen;
= 4.737/6
= 0.7895 moles
But, 1 mole of nitrogen occupies 22.4 liters at STP
Therefore; 0.7895 moles × 22.4 liters
= 17.685 liters
Water has positive side and negative side. This is the reason why water can dissolve salt such sodium chloride. Example when sodium chloride dissociate in water it give Na+ ions and Cl- ions. the negative side of water attack the Na+ ions while the positive side of water attract Cl- ions
Explanation:
Relation between total pressure and mole fraction is as follows.

where,
= partial pressure of gas 1
= mole fraction of gas 1
= total pressure of the gases
Also, it is known that
= 1
or, 
It is given that total pressure of gas mixture is 0.51 atm and partial pressure of helium is 0.32 atm.
Hence, calculate the mole fraction of helium gas present in the given mixture as follows.

0.32 atm = 
= 0.63
As,
= 1
so, 
= 1 - 0.63
= 0.37
Hence, calculate the partial pressure of Ne as follows.


0.3084 atm = 

= 0.834 atm
Thus, we can conclude that the partial pressure of the Ne in the mixture is 0.834 atm.
Explanation:
Fe2+ lose electrons to become Fe 3+ hence oxidized
maO4- is the oxidizing agent