In the first sentence ‘aerie’, which means ‘an elevated often secluded dwelling, structure, or position'is correct. In the second sentence ‘alternate’ would be the correct word as it means ‘occurring or succeeding by turns'. ‘Alternative’ means ‘offering or expressing a choice'. ‘Chandler’ would be appropriate for the third sentence as it means 'a retail dealer in provisions and supplies or equipment'. In the last sentence the correct word would be ‘mantle’ which means ‘a figurative cloak symbolizing preeminence or authority'. ‘Mantel’ means ‘a shelf (usually)above a fireplace'.