作业帮科学九年级上作业本
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科学九年级上作业本
科学九年级上作业本
科学九年级上作业本
1 Failing the test 2 wear uniforms 3 clean up 4 get to class late 5 strict with 6 instead of 7 is good for．1 Jenny is not allowed to watch TV On school nights 2 Jenny has to make the bed before breakfast.
3 Jenny has to wash dishes after dinner on Monday and Friday
4 Jenny is allowed to play computer games on Saturday afternoon
5 Jenny isn’t allowed to chat with friends for a long time On the phone
1 YOu’re not allowed to smoke here 2 You have to keep quiet 3 You’re not allowed to turn right 4 You’re not allowed to park your car here 5 You’re allowed to go across the road
5:!1 is good for 2 At present 3 stay up 4 concentrate,on 5 learn from6 have an opportunity 7 The other day
DCB4.（1）H2SO4+Mg=MgSO4+H2\x18 置换反应 （2）3H2SO4+2Al=Al2（SO4）3+3H2\x18 置换反应 （3）H2SO4+Ba（OH）2=BaSO4↓+2H2O 复分解反应5.氧化铝 氧化 酸性或碱性6.镁 锌 铁 铜 2HCl+Fe=FeCl2+H2\x187.（1）银丝表面无现象,铁丝表面变红色CuSO4+Fe=FeSO4+Cu （2）活动性：铁>铜>银8.D9.因为铁能与硫酸铜溶液反应从而降低药效（CuSO4+Fe=FeSO4+Cu）10.如稀盐酸2HCl+Fe=FeCl2+H2\x18铁 CuCl2+Fe=FeCl2+Cu11.（1）铜 铝 （2）金属活动性的不同.
复习题BCCCBCDA BCABAAAAB18.蓝 H2SO4+CuO=△\x18CuSO4+H2O 19.烧碱（火碱、苛性钠） NaOH 潮解 CO2+2NaOH=Na2CO3+H2O 20.CO2+Ca（OH）2=CaCO3↓+H2O
21 （1）碱 酸 （2）红色刚好消失 （3）HCl+NaOH=NaCl+H2O 22.（1）A （2）不能23.（1）②（2）②H2SO4+Ba（OH）2=BaSO4↓+2H2O 复分解反应24.（1）乙、丙、甲、丁 （2）表面积 25.（1）增大反应物的接触面积,加快与胃酸的作用 （2）氢氧化铝的含量为 214毫克,没有达到标准.它的质量分数为42.8% .26.（1）75% （2）14.6%