2g of a limestone sample(containing CaCO3 as the basic substance) was dissolved in 50cm3 of 1.0M HCl. the resulting solution was made upto 250cm3 with water. 25cm3 of this solution required 11.6cm3 of 0.1M NaOH for neutralization. Calculate the CaCO3 present in the limestone sample. (note: the ratio of HCl to CaCO3 from the balanced reaction equation is 2:1)