Answer:

Explanation:
We need to find the energy for an electron to jump from n = 1 to n = 4.
The energy in transition from 1 state to another is given by :

The difference in energy for n = 1 to n = 4 is:

So, the required energy is equal to
.
A. Base , salt , water,acid
Answer:
78.4 KN/m
Explanation:
Given
mass of person 'm' =80 kg
car dips about i.e spring stretched 'x'= 1 cm => 0.01m
acceleration due to gravity 'g'= 9.8 m/s^2
as we know that,in order to find approximate spring constant we use Hooke's Law i.e F=kx
where,
F = the force needed
x= distance the spring is stretched or compressed beyond its natural length
k= constant of proportionality called the spring constant.
F=kx
---> (since f=mg)
mg=kx
k=(mg)/x
k=(80 x 9.8)/ 0.01
k=78.4x
k=78.4 KN/m
13.6) When any boat displaces a weight of water equal to its own weight, it floats.