Answer:
The wavelength for the transition from n = 4 to n = 2 is<u> 486nm</u> and the name name given to the spectroscopic series belongs to <u>The Balmer series.</u>
Explanation
lets calculate -
Rydberg equation- 
where ,
is wavelength , R is Rydberg constant ( 
), 
and 
are the quantum numbers of the energy levels. (where 
)
Now putting the given values in the equation,
Wavelength 
=
= 486nm
<u> Therefore , the wavelength is 486nm and it belongs to The Balmer series.</u>
The correct answers are :
Changing the volume of the system.
Changing the temperature of the system.
Equilibrium will remain unaffected if the concentration of products and reactants are kept the same, and the temperature of the system is kept constant.
As the system is closed, we cannot add or remove products or reactants.
Change in temperature will shift the chemical equilibrium towards the reactant or product depending on whether the reaction is exothermic or endothermic.
Also change in volume will shift the chemical equilibrium of a chemical reaction if the reactants or products or both are gases.
The volume is 19.76987448 by taking the known variables mass=18.9g and density=0.956g/ml
To get volume you divide the mass by the density which gives you about
19.77 ml in volume
