For an EHV equipment for maintenance first it should be isolated and connected to ground because :

to provide low impedance

to discharge the charging capacitance to ground

protection for operating personnel

both 1) to discharge the charging capacitance to ground and 2) protection for operating personnel

voltage potential at the earth mat increases due to earthing

voltage potential at the earth mat decreases due to earthing

voltage potential at the earth mat remains zero irrespective of fault

none of the above

to provide as low resistance possible to the ground

to provide as high resistance possible to the ground

to provide flow of positive, negative and zero sequence currents

none of the above

increases

decreases

does not effects

none of the above

depth of the electrode

moisture

NaCl

all the above