题目

When he thought of the past, my grandfather would sometimes show us photographs of himself at school．They were brown and faded, and it was hard to believe that the blurred figure of the little boy in the short trousers and socks could ever have been Grandfather．Besides, he wore a cap—and the boys in the photographs wore caps pulled so far forward that half of their faces were obscured．When Grandfather asked us to pick him out from the group, we would surely point to the wrong boy． On one such occasion my younger sister, aged six, burst into tears when Grandfather proudly guided her f在一烧杯中盛有20g CaCl2和NaCl的混合固体粉末，向其中逐渐滴加溶质的质量分数为10.6%的Na2CO3溶液，混合溶液的质量与所滴人Na2CO3溶液的质量关系曲线如图所示．请根据题意回答下列问题：（1）当滴加了100gNa2CO3溶液时，产生沉淀质量为______g．（2）当滴加了120gNa2CO3溶液时，烧杯中溶液中的溶质是______（写化学式）．（3）当滴加了100gNa2CO3溶液时，通过计算求此时所得不饱和溶液中溶质的质量分数．（计算结果精确至0.1%）