如图所示为氢原子的能级图，当氢原子从 n=4 能级跃迁到 n=2 能级时，辐射出光子 a ；当氢原子从 n=3 能级跃迁到 n=1 能级时，辐射出光子 b ，则下列说法中正确的是

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如图所示为氢原子的能级图，当氢原子从 n=4 能级跃迁到 n=2 能级时，辐射出光子 a ；当氢原子从 n=3 能级跃迁到 n=1 能级时，辐射出光子 b ，则下列说法中正确的是（）

A：光子 $a$ 的能量大于光子 $b$ 的能量

B：光子 $a$ 的波长小于光子 $b$ 的波长

C： $b$ 光比 $a$ 光更容易发生衍射现象

D：在同种介质中， $a$ 光子的传播速度大于 $b$ 光子的传播速度

上一题下一题 0.0难度选择题更新时间:2017-11-14 06:19:38

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D

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根据上下文意思，用所给单词的恰当形式完成下列短文。

Toby came back from England yesterday. Two months ago, Toby and his classmate____(enter) a robot competition for his school. More than one hundred ____(school) around the country joined in it, and Toby's school____(win) the first prize. As captain of his team, Toby felt very proud. He said it was a wonderful experience. But the prize sounded more fantastic. It was a holiday in England. “When the plane took off, I still ____(do) think it was real. It was like a dream." Toby said. Someone told Toby that the first prize of the robot competition next time____(be) a holiday in America. Toby hoped to enter it then.

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