Answer:
Sedimentary Rock. You know from the fossils and remains of shells inside. 
Explanation:
If it were igneous, the fossils would be melted away. Maybe not with metamorphic, but it's most likely sedimentary.
 
        
             
        
        
        
Answer:
-2
Explanation:
eACH ELEMENT HAS AN SPECIFIC VALENCE, FOR EXAMPLE, CARBON (+2),+4 IN THE CASE OF OXYGEN IS -2