Mol weight C8H18O4 = 178
It doesn't give litmus test so no cooh group and doesn't give 2,4dnp test so no carbonyl group. It reacts with MeCoCl so only option is it contains hydroxyl groups.
Now mol. weight of product =2*152=304
Gain in weight of reactant per oh unit = 43-1=42
No. of units = 126/42=3