Explanation:
The given AB3 structure has anions B present at ccp (cubic close packing) structure. The cation A is present in the octahedral voids. To determine the percentage of octahedral void occupied, we need to follow the given steps:

Step 1: Calculate the number of octahedral voids present in ccp structure.
In ccp structure, the number of octahedral voids present is equal to the number of close-packed atoms. Since each atom in ccp structure is in contact with 12 other atoms, the number of close-packed atoms is equal to the total number of atoms divided by 2. Therefore, the number of octahedral voids present in ccp structure is given by:
Number of octahedral voids = Total number of atoms/2

Step 2: Calculate the number of cations present in the structure.
The given structure has a formula AB3, which means that there are three anions for every cation. Therefore, the number of cations present in the structure is equal to one-third of the total number of atoms.

Step 3: Calculate the number of octahedral voids occupied by cations.
Since cation A is present in the octahedral voids, the number of octahedral voids occupied by cations is equal to the number of cations present in the structure.

Step 4: Calculate the percentage of octahedral void occupied by cations.
The percentage of octahedral void occupied by cations is given by:
Percentage of octahedral void occupied = (Number of octahedral voids occupied by cations/Number of octahedral voids present) x 100

Final Answer:
By substituting the values obtained from steps 1 to 3, we get:
Percentage of octahedral void occupied = (1/2) x 100 = 50%
Therefore, the percentage of octahedral void occupied by cation A in the given AB3 structure is 50%.