<span>The magnetic field of the Earth serves a useful purpose in deflecting Solar radiation. Without the magnetic field there is much more charged-particle radiation striking the surface. The auroras would occur everywhere instead of at the magnetic poles. Compass needles wouldn't work, and then they would flip direction.. The magnetic field IS DECREASING and could go to zero and reverse sometime in the next few tens-of-thousands of years.</span>
        
             
        
        
        
I would choose Ground meat if i was in a hurry Hope this helps:)
        
                    
             
        
        
        
Mn metal can be used as a sacrificial electrode to prevent the rusting of an iron pipe. So, the correct option is (c) Mn.
Commonly, sacrificial electrodes are employed to stop another metal from corroding or oxidising. A metal that is more reactive than the metal being shielded must serve as the sacrificial electrode. Magnesium, aluminium, and zinc are the three metals most frequently used in sacrificial anodes.
Manganese-Magnesium (Mn-Mg) electrode is more suited for on-shore pipelines where the electrolyte (soil or water) resistivity is higher since it has the highest negative electropotential of the three. In order to replenish any electrons that could have been lost during the oxidation of the shielded metal, the highly active metal offers its electrons. 
Therefore, Mn metal can be used as a sacrificial electrode to prevent the rusting of an iron pipe. So, the correct option is (c) Mn.
Learn more about electrode here:
brainly.com/question/17060277
#SPJ4
 
        
             
        
        
        
Answer:
   Because it uses the residual energy of the fluid used by the first engine.
Explanation:
   A combined cycle power generation counts with two heat engines that work in tandem from the same source of heat. The engines turn the energy into mechanical energy.
   The cycle is much more efficient than the other, almost 60% more.
   I hope this answer helps you.