题目

—Are you free on weekends? —Yes, I am going to have ________ picnic on ________ Sunday. A . the; an B . a; the C . a; / D . an; / 答案：C已知：CH3CH2CH2CH3(g)＋13/2O2(g)===4CO2(g)＋5H2O(l) ΔH＝－2 878 kJ/mol(CH3)2CHCH3(g)＋13/2O2(g)===4CO2(g)＋5H2O(l) ΔH＝－2 869 kJ/mol下列说法正确的是A．正丁烷分子储存的能量大于异丁烷分子 B．正丁烷的稳定性大于异丁烷C．异丁烷转化为正丁烷的过程是一个放热过程D．异丁烷分子中的碳氢键比正丁烷的多