The oxide of metal. x has the. formula xo. which group in the periodic table contains x

HI,
IF IT FORMS AN Oxide of the form XO,
KNOWIng that oxygen has a charge of -2,the element with which it is combined must have a charge of +2 to get a ratio of 1;1
so i think n i'm pretty sure that the answer is the group 2 elements(alkali earth metals) or it may also be a group 6(cuz the have two oxidation states the +2 and +4)
its up to u now,
goodluck

They are like other investigations? say there was a murder u have to do blood test and finger prints which run through a lab. 

Heat is involved in chemical change in two ways; chemical changes either result in heat being added to or removed from an object, and chemical changes require a certain amount of heat before they can take place.