The different reflections of light through two separate mediums causes the bending of wave fronts associated with light rays. The reflection and refraction is caused by the medium associated with its light rays.
        
             
        
        
        
Answer:
C) It reacts explosively with oxygen.
Explanation:
Physical properties are usually those that can be observed using our senses such as color, luster, freezing point, boiling point, melting point, density, hardness and odor. 
What are the Chemical Properties of Hydrogen? They are the characteristics that determine how it will react with other substances or change from one substance to another.
 
        
             
        
        
        
Answer:
22.17 degree
Explanation:
n = 1.52
Angle of incidence, i = 35 degree
Let the angle of refraction is r. 
use the Snell's law
n = Sin i / Sin r 
Sin r = Sin i / n = Sin 35 / 1 .52
Sin r = 0.37735
r = 22.17 degree 
Thus, the ray is refracted at an angle of 22.17 degree. 
 
        
             
        
        
        
A radio telescope is simply a telescope that is designed to receive radio waves from space. In its simplest form it has three components:
1. One or more antennas to collect the incoming radio waves. Most antennas are parabolic dishes that reflect the radio waves to a receiver, in the same way as a curved mirror can focus visible light to a point.
2. A receiver and amplifier to boost the very weak radio signal to a measurable level. These days the amplifiers are extremely sensitive and are normally cooled to very low temperatures to minimise interference due to the noise generated by the movement of the atoms in the metal (called thermal noise).
3. A recorder to keep a record of the signal. Most radio telescopes nowadays record directly to some form of computer memory disk as astronomers use sophisticated software to process and analyse the data.
 
        
             
        
        
        
The atom has 71 protons.
(The atomic number of a chemical element is the number of protons found in the nucleus of an atom)
hope this helps