在玻尔的原子模型中,比较氢原子所处的量子数n=1及n=2的两个状态,若用E表示氢

题型:选择题

问题:

在玻尔的原子模型中,比较氢原子所处的量子数n=1及n=2的两个状态,若用E表示氢原子的能量,r表示氢原子核外电子的轨道半径,则(   )

A.E2>E1 r2>r1

B.E2>E1 r2<r1

C.E2<E1 r2>r1

D.E2<E1,r2<r1

考点:原子核的组成
题型:选择题

鉴定某脱脂淡奶粉是否为伪劣产品,不需要用的化学试剂是[ ]

A.斐林试剂

B.苏丹Ⅲ染液

C.双缩脲试剂

D.甲基绿

题型:选择题

维生素A缺乏时,可以出现的缺乏症有()

A.毛囊角化

B.脂溢性皮炎

C.皮下出血

D.皮疹

E.对称性皮炎

题型:选择题

足三里穴位于小腿前外侧,当()下3寸,距胜骨前峪1横指。

A、膝眼

B、外膝眼

C、内膝眼

D、内外膝眼

题型:选择题

以下程序的执行结果是 【8】
a=15.5635
b=Int(a*100+0.5)/100
Print b

题型:选择题

"I would almost rather see you dead." Robert S. Cassatt, a leading banker of Philadelphia, shouted when his twenty-year-old eldest daughter announced that she wanted to become an artist.
In the 19th century, playing at drawing or painting on dishes was all right for a young lady, but serious work in art was not. And when the young lady’s family ranked among the best of Philadelphia’s social families, such an idea could not even be considered.
That was how Mary Cassatt, born in 1844, began her straggle as an artist. She did not tremble before her father’s anger. Instead; she opposed him with courage and at last made him change his mind. Mary Cassatt gave up her social position and all thought of a husband and a family, which in those times was unthinkable for a young lady. In the end, after long years of hard work and perseverance, she became America’s most important woman artist and the internationally recognized leading woman painter of the time.

What made Mary Cassatt’s "struggle" to become a recognized artist especially hard
[A] She was a woman.
[B] Her father opposed her.
[C] She had no social position.

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