JEE Advanced levelSingle correct optionDifficulty 3 of 3pb039
3.7g of Ca(OH)X2 is present in water as lime water. COX2 is bubbled in until the initially formed milkiness just disappears. Taking Ca=40, C=12, O=16, H=1, the maximum mass of CaCOX3 formed and the total mass of COX2 used are respectively
A5.0g and 2.2g
B10.0g and 4.4g
C5.0g and 4.4g
D2.5g and 4.4g
Answer: C
n(Ca(OH)X2)=3.7/74=0.05mol. First Ca(OH)X2+COX2CaCOX3+HX2O gives 0.05molCaCOX3=5.0g (maximum) using 0.05molCOX2. Then CaCOX3+COX2+HX2OCa(HCOX3)X2 needs another 0.05mol. Total COX2=0.10×44=4.4g.