Why is the oxidation state of o2- more likely than o6+ explain ?

Because more energy is required to form ion.

Explanation:

Oxygen is the 8th element of the periodic table which belongs to Group 16.

The electronic configuration of the element is:

The number of valence electrons are 6 which is not a stable electronic configuration.

To attain stable electronic configuration, this element will either loose 6 electrons to form ion or gain 2 electrons to form ion.

The loosing of 6 electrons require a huge amount of energy and is an unfavorable reaction. Hence, this element will gain 2 electrons easily and form ion.

This element is considered as a non-metal because it gains electron to attain stable electronic configuration.

c. because step up transformer steps up the input voltage i.e increases the input voltage  

the number of turns are greater on the secondary side of step up transformer  

transformer does not handle dc current

i think its 100

i hope this !