Earth's atmosphere blocks many types of light including gamma, x-rays most ultraviolet and infrared. So optical telescopes that use visible light and ultraviolet telescopes that are used to study very hot stars are much less effective on Earth.
The gas is in a rigid container: this means that its volume remains constant. Therefore, we can use Gay-Lussac law, which states that for a gas at constant volume, the pressure is directly proportional to the temperature. The law can be written as follows:

Where P1=5 atm is the initial pressure, T1=254.5 K is the initial temperature, P2 is the new pressure and T2=101.8 K is the new temperature. Re-arranging the equation and using the data of the problem, we can find P2:

So, the new pressure is 2 atm.
Answer:5
Explanation:
Given
speed of object 
radius of circle 
Force towards the center 
Work done is given by the dot product of Force and displacement
and we know know displacement of the object is along the circle which is perpendicular to the force acting therefore Work done will be zero


Answer:
18.89cm
Explanation:
As we know that the person is standing 5m in front of the camera

The focal length of the lens =50cm
f=50 cm
By Lens formula we have:

By the formula of magnification

The height of the image formed is 18.89cm.
Answer:
The volume of copper is 2.198 ml
Explanation:
Given;
mass of copper, m = 20 g
density of copper, ρ = 9.1 g/ml
Density is given by;
Density = mass / volume
Volume = mass / density
Volume = (20 g) / (9.1 g/ml)
Volume = 2.198 ml
Therefore, the volume of copper is 2.198 ml