Which valences have the greatest tendency to form ions?
1)+1
2)-1
3)+2
4)-2
5)+3
6)-3
7)+4
8)-4
you can pick more then one

i believe that the answer is c.

the answer is:

carbon dioxide

glacial erosion, the picking up and movement of earth beneath a glacier, is also referred to as plucking. erosion and transportation of individual pieces of bedrock, especially large "joint block occur as a result of this glacial erosion. plucking is type of erosion in which rocks become frozen into the bottom and sides of the glacier.as the glacier moves downhill it 'plucks' the rocks frozen into the glacier from the ground.