静电喷涂时,为保证手工操作者的安全,对用电有何要求?()
A、高电阻
B、低电阻
C、中等电阻
D、低电压
参考答案:A
小题1:That’s an (interest) computer game.
小题2:Can you (bring) your photos to school.
小题3:She is from France,so she can speak (France ) very well.
小题4:The animals in the zoo are from different (country).
小题5:She practices (play) the piano every day.
小题6:Listen!The girl (sing) in the room.
小题7:The Greens (take)lots of photos on the beach yesterday.
小题8:Mike is funny.He always make us (laugh).
小题9:Peaple can’t live (with) water.
小题10: (luck),he missed the train.
(10分)工业盐中含有NaNO2,外观和食盐相似,有咸味,人若误食会引起中毒,致死量为0.3g~0.5g。已知NaNO2能发生如下反应:2NO + xI-+ yH+ = 2NO↑+ I2 + zH2O,请回答下列问题:
(1)上述反应中,x的数值是 ,y的数值是 。
(2)根据上述反应,可用化学试纸的生活中常见物质进行实验来鉴别工业盐和食盐,现
有碘化钾淀粉试纸,则还需选用的生活中常见物质的名称为 。
(3)某工厂废切削液中含有2%—5%的NaNO2,直接排放会造成水污染,但加入下列
物质中的某一种就能使NaNO2转化为不引起污染的N2,该物质是 ,
a.NaCl b.H2O2 c.NH4Cl d.浓H2SO4
所发生反应的离子方程式为: 。