Answer:
I would say the last one because mass is not created nor destroyed. 
Explanation:
 
        
             
        
        
        
Landsat - (USA)
Spot - (France)
Radarsat (Canada)
        
             
        
        
        
Answer:
The pH of a solution is a measure of the molar concentration of hydrogen ions in the solution and as such is a measure of the acidity or basicity of the solution.
 
        
             
        
        
        
Answer:
true
Explanation:
Materials science is an interdisciplinary field involving the properties of matter and its applications to various areas of science and engineering. It includes elements of applied physics and chemistry, as well as chemical, mechanical, civil and electrical engineering.
and we all know matter involve solid liquid or gas