问题 问答题

用数字和化学符号表示:

(1)2个氯原子______;    (2)铵根离子______;

(3)5个氮气分子______;  (4)硫酸铁中硫元素显+6价______.

(5)构成氯化钠的微粒是______和______.

答案

(1)根据原子的表示方法:用元素符号来表示一个原子,表示多个该原子,就在其元素符号前加上相应的数字.因此2个氯原子表示为:2Cl;故答案为:2Cl;

(2)根据离子的表示方法: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.若表示多个该离子,就在其元素符号前加上相应的数字;因此铵根离子表示为:NH4+;故答案为:NH4+

(3)根据分子的表示方法:正确书写物质的化学式,表示多个该分子,就在其化学式前加上相应的数字,因此5个氮气分子表示为:5N2;故答案为:5N2

(4)根据元素化合价的表示方法:确定出化合物中所要标出的元素的化合价,然后在其化学式该元素的上方用正负号和数字表示,正负号在前,数字在后,因此硫酸铁中硫元素显+6价表示为:

+6
Fe2(SO4)3

故答案为:

+6
Fe2(SO4)3

(5)构成氯化钠的微粒是钠离子和氯离子,根据离子的表示方法,表示为:Na+、Cl-; 故答案为:Na+;Cl-

问答题
单项选择题

Few scientific fields are as full of risk as that of research into human intelligence. The two questions that (1) over and over again are "is it a result of nature or nurture" and "does race make a difference"

Making (2) comments about the second question can be a (3) move, as James Watson, a co-discoverer of DNA structure, recently found. He suggested that he was " (4) about the prospect of Africa" (5) "all our social policies are based on the fact that their intelligence is the same as ours (white people) (6) all the testing says not really". Such (7) by Dr. Watson are not merely (8) , they are scientifically weird. If the term (9) has any useful scientific meaning, then Africa, the continent where modern humanity began, is most racially diverse. The resulting (10) among the public forced Dr. Watson to leave his laboratory.

(11) , the study of the first question (12) between intelligence and genetics— has some wiser practitioners. One of them, Terrie Moffitt, of King’s College, has just (13) a project judging the relative importance of nature and nurture. Dr. Moffitt’s team (14) the effect on intelligence of breastfeeding, but in a genetic context. Previous studies have shown that breastfed children are more intelligent, (15) about six IQ points, than those given baby formulas.

The team, however, (16) the involvement of a gene called FADS2, which comes in two varieties, known as C and G. The researchers (17) if these two varieties interacted differently with breast milk. (18) on data from two groups of people, they found that the intelligence increase associated with breastfeeding only happened to people having (19) at least one copy of the C variety. The effect did not. (20) on the social classes or IQs of the parents.

6()

A.however

B.whereas

C.since

D.as