钡和钠相似，也能形成含的过氧化物，下列叙述中不正确的是( ) A．过氧化钡的化学

常温下，下列各组离子在指定溶液中一定能大量共存的是

A．滴入酚酞溶液显红色的溶液中：K^＋、Na^＋、Cu^2＋、

B．加入过量NaOH溶液或少量稀H₂SO₄时，都能产生白色沉淀的溶液：Al^3＋、Ba^2＋、Cl^－、

C．水电离产生的c(H^＋)＝10^－13mol·L^－1的溶液中：Na^＋、Cl^－、、

D．0.1 mol·L^－1HNO₃溶液中：Mg^2＋、、Fe^2＋、Cl^－

Melissa and LoveLetter made use of the trust that exists between friends or colleagues.Imagine receiving an （） from a friend who asks you to open it. This is what happens with Melissa and several other similar email （） . Upon running, such worms usually proceed to send themselves out to email addresses from the victim’s address book, previous emails, web pages （） . As administrators seek to block dangerous email attachments through the recognition of well-known （） , virus writers use other extensions to circumvent such protection.Executable (.exe) files are renamed to .bat and .cmd plus a whole list of other extensions and will still run and successfully infect target users. Frequently, hackers try to penetrate networks by sending an attachment that looks like a flash movie, which, while displaying some cute animation, simultaneously runs commands in the background to steal your passwords and give the （） access to your network.

This is what happens with Melissa and several other similar email（）.

A．virtual

B．virus

C．worms

D．bacteria

已知辛烷的燃烧热为5518kJ·mol^－1，强酸与强碱在稀溶液中发生反应时的中和热为

57.3kJ·mol^－1，则下列热化学方程式书写正确的是

①C₈H₁₈（l）+25/2O₂（g）  8CO₂（g）+9H₂O（g）；△H=－5518kJ·mol^－1

②2C₈H₁₈（l）+25O₂（g）  16CO₂（g）+18H₂O（l）；△H=－11036kJ·mol^－1

③H⁺(aq)  + OH^－(aq)     H₂O(l)； △H=" " +57.3kJ·mol^－1

④2NaOH(aq) +H₂SO₄(aq)    Na₂SO₄(aq) + 2H₂O(l)；△H=－57.3kJ·mol^－1     

A．①③

B．②③

C．②④

D．只有②

甲通过电子邮件回复乙同意购买木材的要约，乙的主营业地在A市B区，但乙在其位于A市C区的常住地接收了电子邮件。该合同的成立地点是A市C区。

极富冒险精神；收入水平、社会地位和受教育程度较高；一般是年轻人，交际广泛且信息灵通。这类群体属于（）。

A.创新采用者

B.早期大众

C.早期采用者

D.落后采用者