Answer:

Explanation:
If we have a net force F acting on a body of mass m it will experiment an acceleration a. Newton's 2nd Law gives us the relation between these quantities: F=ma.
In our case, we want to calculate the acceleration, so we write:

With the values we have we get:

1. Frequency 2. measure from trough to trough
mass number is defined as sum of number of protons and neutrons
so here for Isotope A
Isotope A contains 56 protons and 80 neutrons.
Mass number will be given as

For Isotope B
Isotope B contains 55 protons and 81 neutrons.

For Isotope C
Isotope C contains 57 protons and 80 neutrons.

For Isotope D
Isotope D contains 56 protons and 74 neutrons.

<em>So here Isotope A and Isotope B has same mass number</em>
1 and 4 are tire.
2 and 3 are not.