航天技术中的火箭推进剂可用醇类为燃料，液态氧为氧化剂，但后者的沸点较低(﹣183℃)，需要额外的隔热装置，因而增加了火箭的重量．为了避免此缺点，可用过氧化氢(H2O2)代替液态氧，它具有相对高的沸点和较低的凝固点，而且没有毒性，和醇反应时也能放出很高的能量．现有一液体推进剂以醇(含碳52%、含氢13%、含氧35%)为燃料，质量分数为90%的过氧化氢做氧化剂，欲使1kg该醇燃料完全燃烧，计算需消耗质量分数为90%的过氧化氢的质量(提示：可按2H2O2=2H2O+O2↑得到的氧气与醇反应来计算)．
4904g．
Reuben, a 12-year-old boy, saw something in a shop window. But the price—five dollars—was far beyond his means. He couldn’t ask his parents the money. His father made a living through in Bay Roberts. His mother, Dora, tried hard to feed and clothe their five children. Hesitating(犹豫) for a few minutes, he opened the and talked to the shopkeeper. “…I don’t have the money right now. Can you please it for me?” “I’ll try,” the shopkeeper smiled. Reuben respectfully touched his worn cap and walked out. Hearing the sound of hammering from a side street, he suddenly had a(an) . He ran towards the sound and stopped at a construction site(建筑工地).Reuben knew he could collect the discarded nails(被丢弃的钉子) and sell them to the factory for five cents . He looked for nails until sunset. Then he ran to the factory and sold them. Reuben tightly clutched(握紧) the five-cent pieces and ran home. He found a rusty iron can and dropped his inside. Then he rushed into the barn(谷仓) near his house and hid it. It was dinner time when Reuben got home. His father sat at the big kitchen table, working on a fishnet. Dora was at the kitchen stove, ready to serve as Reuben took his place at the table. Looking at his mother, Reuben smiled. Every day after school, Reuben searched the town, trying to finish his task. Finally, the time had come! He ran into the barn, opened the can, poured the coins out and began to count. He still needed 20 cents! He had to sell four nails the day ended. Rushing to the town, Reuben searched every corner. It was getting dark when Reuben arrived at the factory. The man at the factory was about to . “Please, mister. I have to sell these nails now—please.” “Why do you need this money so ?” “It’s a secret.” The man took the nails, reached into his pocket and put four coins in Reuben’s hand. Clutching the can tightly, Reuben for the shop. “I have the ” he solemnly told the owner. Back home, his mother was cleaning the kitchen. “Here, Mum! Here!” Reuben shouted as he ran to her. He a small box in her roughened hand. She opened it carefully. A blue-velvet jewel box appeared. Dora lifted the lid(盖子). Tears began to blur(模糊) her vision. In gold lettering on a small, almond-shaped brooch(胸针) was the word Mother. It was Mother’s Day, 1946.
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2NH3，下列说法错误的是