Answer:
0.1389mol
Explanation:
no of mol of Al in 7.5g=7.5g/27gmol^-1
=75/270mol
according to tge chemical equation
2mol of Al:1 mol of Al2S3
1mol of Al:0.5mol of Al2S3
therefore 75/270 mol of Al : 0.5*75/270 mol of Al2S3
=0.1389mol