Answer:
C. a dense region of positive charge existed somewhere in the atom.
Explanation:
Physicist Ernest Rutherford created the gold foil experiment in which he shot a beam of alpha particles at a sheet of gold foil, which then sent a  few of the particles flying after they were deflected. Based on the information gathered after completing this experiment, Rutherford concluded that a dense region of positive charge existed somewhere in the atom.
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An electric motor is an electrical machine that converts electrical energy into mechanical energy.
Electric motors work on the principal of the interaction between magnetic field electr-magnetism. A loop which is carrying the current is placed in a magnetic field. The loop will experience a torque. The torque starts rotating the coil and the propellers start to rotate when the current passes through the loop.
        
                    
             
        
        
        
The answer is Carbonic acid
        
                    
             
        
        
        
Answer:
Answer  for the question is given in the attachment.
Explanation:
 
        
             
        
        
        
Definitely D. The brakes on a bike rub against the wheel. Not sure about the others.