Percent composition. Please help meee :(

Explanation:

Formula of percent composition:

% X = ( mass of element in compound / total mass of compound ) × 100

11) Al₂O₃

Al = 27 g/mol

O = 16 g/mol

%Al = (54 / 101.96) × 100

%Al = 52.9%

%O = (48 / 101.96) × 100

%O = 47.1%

12) C₅H₅O₅

C = 12 g/mol

H = 1 g/mol

O = 16 g/mol

C% = (60 / 145 ) × 100

C% =41.4%

H% = (5 / 145 ) × 100

H% =3.4%

O% = (80 / 145 ) × 100

O% = 55.2%

13) BaBr₂

Ba = 137.3 g/mol

Br =79.9 g/mol

Ba% = (137.3 / 297.14) × 100

Ba% = 46.2%

Br% = (159.8/ 297.14) × 100

Br% = 53.8%

14) Fe₃(PO₃)₂

Fe = 55.8 g/mol

P = 31 g/mol

O = 16 g/mol

Fe = (167.4/325.48)  × 100

Fe = 51.43%

P = (62/325.48)  × 100

P = 19.05%

O = (96 /325.48)  × 100

O = 29.49%

i believe the answer is a.

i think it's c. i'm not sure but i think so.