一种化学冰袋含有Na2SO4•10H2O和NH4NO3，用时将它们混合并用手搓揉_爱下问搜题

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问题选择题

一种化学冰袋含有Na₂SO₄•10H₂O和NH₄NO₃，用时将它们混合并用手搓揉就可制冷，且制冷效果能维持一段时间．以下关于其制冷原因的推测中肯定错误的是（　　）

A．Na₂SO₄•10H₂O脱水是吸热过程

B．较长时间制冷是由于Na₂SO₄•10H₂O脱水过程较慢

C．Na₂SO₄•10H₂O在该条件下发生的复分解反应是吸热反应

D．NH₄NO₃溶于水会吸收热量

答案

A、Na₂SO₄•10H₂O脱水是吸热过程，故A正确；

B、因为十水硫酸钠脱水较慢，它一点点地脱水，水遇上硝酸铵吸热，因此制冷效果可以维持较长，故B正确；

C、Na₂SO₄•10H₂O和NH₄NO₃不能发生复分解反应，故C错误；

D、硝酸铵夺取硫酸钠结晶水，是一个吸热反应，同时溶解吸热，故D正确；

故选C．

多项选择题

下面可能导致喉返神经麻痹的疾病的有（）

A.颅底骨折

B.食管癌

C.甲状腺癌

D.流行性感冒

E.脑出血

完形填空

It was very cold at 7 am that Monday morning in Harvard Square. I was nearly mad because I had just         the bus, and was standing out in the freezing cold waiting for the next one. My mind was filled with anxiety and        thoughts. “Why didn’t I leave two minutes       ?”
       the others at the bus stop was a woman in her fifties wearing a old-fashioned hat, an old pair of boots and a dark coat, but she had no       . Another woman, who looked to be in her middle twenties, said to the        woman, “Your hands must be very cold. You’ll get frostbitten (冻伤的) in this weather.” She        her heavy backpack to the ground, bent down, and began        for something inside her backpack. The older woman looked       and said, ”Oh no, that’s OK. I’m        .
The younger woman continued to search        in her backpack and the older woman kept repeating, “Don’t        yourself. I’ll be all right.” After       seemed like so many minutes, the younger woman        a pair of purple gloves. She took the older woman’s hands and gently      a glove on each hand, covering one finger       . The older woman said, “Thank you. You’re so sweet.”
Though I was very cold, the act of        gave ma a warm feeling inside. It also motivated me to buy five pairs of purple gloves, similar to hers, and        them in my bag, just in case I        someone who was in great        on a cold day.

D．at the same time

B．came across