Answer:
Cu
Explanation:
Groups 3 - 12 (or groups IIA - IIB) of the periodic table contain transition elements. Transaction elements start from period four (4) of the periodic table. The phrase alludes to the fact that the d sublevel is filling at a lower main energy level than the s sublevel that came before it.
The transition elements' arrangement is inverted from the fill order, with the 4 s filled prior to the actual 3 d begins. The transition elements are commonly referred to as transition metals since they are all metals. They are less reactive than the metals in Groups 1 and 2 and have normal metallic characteristics.
From the options given Cu is the only transition metal in the fourth period on the periodic table.
Are you speaking of a density gradient, in which a more concentrated solution moves below a less concentrated solution?
In that case, the more concentrated solution has the greater density, and it will gradually sink below the less concentrated solution.
In the same way, a stone will sink in water, which is less dense than the stone.
Answer :
(a) The energy of blue light (in eV) is 2.77 eV
(b) The wavelength of blue light is 
Explanation:
The relation between the energy and frequency is:
where,
h = Plank's constant = 
Given :
Frequency = 
Conversion used :
So,
Also,
So,
The energy of blue light (in eV) is 2.77 eV
The relation between frequency and wavelength is shown below as:
Where,
c = the speed of light = 
Frequency = 
So, Wavelength is:
Conversion used : 
The wavelength of blue light is
