The concept required to solve this problem is hydrostatic pressure. From the theory and assuming that the density of water on that planet is equal to that of the earth
we can mathematically define the pressure as

Where,
= Density
h = Height
g = Gravitational acceleration
Rearranging the equation based on gravity

The mathematical problem gives us values such as:



Replacing we have,


Therefore the gravitational acceleration on the planet's surface is 
Explanation:
Atoms are the components of ordinary matter, also called baryonic matter, which only represents 4% of the universe, while the remaining 96% would be formed by what is known as dark matter and dark energy which constitute two of the unsolved problems in physics.
There is a positive correlation between luminosity and mass of stars, meaning the more luminous a star is, the more massive it is likely to be as well. Given this, the masses of the stars should be in descending order of brightness.
Star 1 is the most luminous, so it should be heaviest, and the luminosity descends to Star 4.
Option B is the only chart that conforms to this, so it is the answer.
Answer is B
#1
As we know that energy of electromagnetic wave is given by

so here we know that penetrating power will directly depends on its energy and energy inversely depends on wavelength
So here we can say correct answer will be
C) The penetrating power decreases as the wavelength increases.
#2
Speed of sound is maximum in solids and minimum in gas
so here as ice melts into water the speed of sound must have to decrease
so correct answer will be
D) The speed of sound would decrease because sound travels faster through solids than liquids.
#3
mechanical waves required medium to travel while non mechanical waves do not require any medium to travel
so here correct answer will be
A) sound
The average speed is the ratio between the total space and the total time of the motion:

The total space is

while the total time is

So, the average velocity is

We can also rewrite it in m/s. The total space is

, while the time is

, and so