Protons and neutrons in an atom are held together by a nuclear energy also called the strong force.
The figure shown above is series combination as the two resistors (bulb) are there which are then connected to the battery
so i conclude from the above options given the option is B
hope it helps
Answer:
the energy difference between adjacent levels decreases as the quantum number increases
Explanation:
The energy levels of the hydrogen atom are given by the following formula:

where
is a constant
n is the level number
We can write therefore the energy difference between adjacent levels as

We see that this difference decreases as the level number (n) increases. For example, the difference between the levels n=1 and n=2 is

While the difference between the levels n=2 and n=3 is

And so on.
So, the energy difference between adjacent levels decreases as the quantum number increases.
Answer:
Time taken by A and B is 1.2 hr.
Explanation:
Given that
Time taken by tank when all(A+B+C) are open = 1 hr
Time taken by tank when A+C are open = 1.5 hr
Time taken by tank when B+C are open = 2 hr
If we treat as filling of tank is a work then
Work = time x rate
Lets take work is 1 unit
1 = 1(1/a+1/b+1/c) ---------1
1 = 1.5(1/a+1/c) ----------2
1 = 2(1/b+1/c) --------3
From equation 1 and 3
1=1(1/a+1/2)
a=2
Form equation 2
1 = 1.5(1/2+1/c)
c=6
From equation 3
1 = 2(1/b+1/6)
b=3
So time taken by
A is alone to fill tank is 2 hr
B is alone to fill tank is 3 hr
C is alone to fill tank is 6 hr
So 
Time taken by A and B is 1.2 hr.