To develop this problem it is necessary to apply the concept of Frequency based on speed and wavelength.
According to the definition the frequency can be expressed as

Where,
v = Velocity
Wavelength
Our value are given by,
v = 345m/s

Replacing


Therefore the frequency of the tuning fork is 547.61Hz
The snail’s speed is 0.001042. Hope this helps!
1. Frequency: 
The energy given is the energy per mole of particles:

1 mole contains a number of Avogadro of particles,
, equal to
particles
So, by setting the following proportion, we can calculate the energy of a single photon:

This is the energy of a single photon; now we can calculate its frequency by using the formula:

where
is the Planck's constant
f is the photon frequency
Solving for f, we find

2. Wavelength: 
The wavelength of the photon is given by the equation:

where

is the speed of the photon (the speed of light). Substituting,

S = d/t, s = 120, d = 2000, t = ?
Input the values,
120 = 2000/t
Make t the subject of the formula by cross multiplying, Therefore,
120t = 2000
Divide both sides by 120
t = 16.7hrs to 1 decimal place.
If you're asked to convert it, you can.
To analyze the differences in acceleration of the two objects, a necessary formula/relation to remember here is force = mass * acceleration. Given the different data in the problem, we can solve for the acceleration of each object. This is shown below:
Force = 15 N
M1 = 25 kg
M2 = 50 kg
a1 = ?
a2 = ?
For object 1:
15 N = 25 kg * a
a = 0.6
For object 2:
15 N = 50 * a
a = 0.3
Therefore, the acceleration of Object B is half that of Object A.