题目

请按下列要求填空：（1）中的化合价是__________ （2）2个铵根离子_______ （3）硫酸铝的化学式_______ 答案：【答案】+5【解析】（1）中钾元素的化合价为+1价，氧元素的化合价是-2价， 设氯元素的化合价是x，根据化合价的代数和为0，+1+x+（-2）×3=0，解得x=+5.（2）离子的表示方法，在表示该离子的元素符号右上角，标出该离子所带的正负电荷数，数字在前，正负符号在后，带1个电荷时，1要省略，若要表示多November 9 is a time for us to learn a lot more about fire(火). This is what to do in a fire:1.Shout out. Shout as loudly as you can, because people may be asleep.?2.Call 119. Never try to put out a fire yourself. Tell 119 where you are and what is on fire.?3.Keep down close to the floor. There is less smoke down there, so it’s easier to breathe and see where you are going.?4.Test the door. If the door is cool, open it carefully. If the door is hot, do not open it! Try to find a different way out.?5.Get out. Do not stop to pick up anything. A fire can become very big in a few seconds!?6.Don’t use the lift. Always use the stairs. The lift may go wrong and keep you inside.?7.Don’t go back .Even if you have left your pet or favorite toy inside, do not go back for it. Animals have a very good sense of smell. They often get out of buildings before people.【小题1】When is the National Fire Prevention Day(消防日)?A．December 9B．November 9C．November 11D．September 11【小题2】How many things should we do according to the passage?A．sixB．eightC．sevenD．five【小题3】According to the passage, when something is on fire, you must ________at once.A．look for your petB．telephone 119C．call 120D．put out the fire yourself【小题4】You should keep down close to the floor because_________.A．there is less smoke down thereB．the firemen can find you easilyC．people may be asleepD．you should look after your things carefully【小题5】Which of the following is not right according to the passage?A．If the door is hot, try to find a different way out.B．Don’t use the lift.C．People often get out of buildings before animals.D．Do not stop to pick up anything.