2HCl+CaCO3====CaCl2+H2O+CO2↑ △m
100 44
x 10g+90g-97.14g
x=2.86g×100÷44=6.5g
故ω(CaCO3)=6.5g÷10g×100%=65%
答:鸡蛋壳中碳酸钙的质量分数为65%.