<span>These are isotopes of carbon and they all contain 6 protons and 6 electrons but each contains a difference number of neutrons - 6, 7, and 8 respectively.
^ This is the answer because an isotope changes the atomic mass, NOT atomic number. That means that the neutrons are changed, not the protons. </span>
Answer:

0.3619sec
Explanation:
Given that
Mass,m=148 g
Length,L=13 cm
Velocity,u'(0)=10 cm/s
We have to find the position u of the mass at any time t
We know that

Where 

u(0)=0
Substitute the value

Substitute u'(0)=10


Substitute the values

Period =T = 2π/8.68
After half period
π/8.68 it returns to equilibruim
π/8.68 = 0.3619sec
Answer:
P = 0.25 W
Explanation:
Given that,
The emf of the battry, E = 2 V
The resistance of a bulb, R = 16 ohms
We need to find the power delivered to the bulb. We know that, the formula for the power delivered is given by :

So, 0.25 W power is delivered to the bulb.