This means to come up with your own hypothesis or assumptions of something because there is some missing information or not clearly stated. 
 
        
             
        
        
        
Answer: Abiotic factor for polar: Ice
Abiotic for desert: Sand
Biotic for polar: Polar bears
Biotic for desert: Cacti
The types of factors are different because there are different set conditions for each ecosystem. A cactus is built for it's hot, dry ecosystem. If it were to move to a polar ecosystem it would not survive there. Same for the polar bear. It's built for polar regions. It has white fur to blend with the white ice to help it blend in and it's adapted to swim to get it's food source.
Explanation:
 
        
                    
             
        
        
        
5 atm pressure must be applied to compress the gas to a volume of only 150.0 ml.
<h3>Given</h3>
Mass of oxygen at room temperature =500.0 ml
Volume of pressure = 50 atm pressure.
The gas to a volume = 150.0 ml
<h3>Explanation</h3>
The volume decreases by the factor = 500.0 mL / 150.0 mL
                                                              = 10 / 3
The pressure of the gas increased by a factor of 10/3 , which would make its final value equal to

           = 5.00 atm
So, 5 atm pressure must be applied to compress the gas to a volume of only 150.0 ml.
Learn more about mass of oxygen here:
brainly.com/question/12902286
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D. He has an aerator that pumps bubbles into the tank