Answer:
Shadows are made by blocking light. Light rays travel from a source in straight lines. If an opaque (solid) object gets in the way, it stops light rays from traveling through it. This results in an area of darkness appearing behind the object. The dark area is called a shadow
 
        
                    
             
        
        
        
The number of predators and preys change from time to time following
cycles. Whenever there is fewer prey, predators start dying because they
have not enough to eat; however, that provokes the population of prey
to be increased while there are fewer predators. So if suddenly the
number of prey gets bigger, regardless of the number of predators, the
cycles get disturbed by this sudden occurrence. The predators will get
more to hunt, therefore getting more violent.
        
             
        
        
        
The correct option is A.
An exponential growth is a type of growth whose rate becomes more rapid in relation to the total number that is available. When a specie has newly been introduced into a new area, they usually give birth rapidly and take over their new environment. If you check the options given above, you will see that it is only option A that have numbers that continuously increase. An exponential growth increase continuously. <span />
        
             
        
        
        
Answer: 
c) solar energy is renewable because it will be available as long as the sun continues to burn
To be specific, it's indistinguishable
 
        
             
        
        
        
Answer:A material designed to produce passive solar energy can achieve energy savings of 70%. In addition to this great advantage, we show you what are the main benefits that passive solar energy can bring us:
Reduced maintenance cost. Since it has no external equipment to harness the energy, the maintenance required will be practically nil.
It is 100% renewable energy. It does not emit polluting gases and helps to maintain the environment, in addition to being an inexhaustible source which is the sun and we can always have it.
Energy and economic savings.  
Reduction in the cost of electricity and gas bills.  
Compatible with solar panel installations. In fact, it is currently considered as a complementary technology.  
APPLICATIONS :Active solar energy is mainly used to obtain sanitary hot water, heating systems and to transform solar radiation into electrical energy.
Active solar technology is also used to produce air currents for ventilation or cooling and to store heat for later use. In any of these processes, the use of pumps and fans is required.
Other uses of active solar energy are:
Water purification.
Drying.
Evaporation.
Distillation.
Solar batteries.
Solar chargers.
Energy for street lighting, traffic signals and roads.