#1: The element that loses electrons in a chemical reaction is said to have been which of the following?
A. reduced
 B. oxidized
 C. combusted
 D. rusted
 **idk, is it reduced or oxidized??
Answer: oxidized. The element that loses electrons increases its oxidation number (becomes more positve or less negative) and this is oxidation. 
Which type of reaction occurs if one element gains electrons and another loses electrons?
 A. combustion
 B. synthesis
 C. oxidation-reduction
 D. double-displacement
 **my answer: C
Yes, oxidation-reduction
 #3: What is the oxidation number for phosphorus in H4P2O7?
 A. +5
 B. +3
 C. +1
 D. - 1
 **my answer: A. +5
This is the way to calculate it 4(+1) + 2x + 7(-2) = 0 => x = +5 
 #4: What is the oxidation number for phosphorus in Na2HPO3?
 A. +5
 B. +3
 C. +1
 D. - 1
 **my answer; B. +3
 is that right??
Right
2(+1) + 1 + x + 3(-2) = 0 => x = 6 -1 -2 = 3 (positive)
        
                    
             
        
        
        
Answer:
C. An external voltage source
Explanation:
An electrolytic cell converts electrical energy from an external voltage source into chemical energy that drives a reaction. 
The external voltage source is usually a battery. This energy form generated from the battery helps to drive chemical reactions. 
The process involves the decomposition of an ionic compound by means of current passed into the aqueous or molten form of the compound through conductors known as electrodes.