题干

下表列出了某短周期元素R的各级电离能数据(用I1、I2……表示,单位为kJ·mol-1)。

I1

I2

I3

I4

……

R

740

1 500

7 700

10 500

……

下列关于元素R的判断中一定正确的是(  )

A:R的最高正价为+3价

B:元素R位于元素周期表中第ⅡA族

C:元素R的原子最外层共有4个电子

D:元素R基态原子的电子排布式为1s22s2

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答案(点此获取答案解析)

B

同类题5

根据短文内容的理解,选择正确答案。

    I didn't think I had a passion(激情). I would sit in front of the TV all day, thinking about nothing but the next show. It was not long ago that I first learned how important having a passion is to life.

    That day I went with my mum to drive my sister to the gym. I was bored. Then, as my mum stopped at a red light, someone on the side of the road caught my eye(吸引我的世界). It was a man dressed in rags (衣衫褴褛). He was homeless. That didn't interest me, for I had seen many like him before.

    But in some ways he was different. This man was not sitting down with a sad expression(表情). He had a radio in his hand and was dancing happily to the music. The radio seemed to be the most precious(珍贵) thing he had.

    "Mum, why does that man have a radio even thought(尽管) he's homeless?" I asked.

    "He bought it," she replied. I was still unable to understand.

    "But if he's homeless, why doesn't he use the money to buy food or clothes? He wasted it on something he doesn't need."

    "Well, Sarah, sometimes food and clothes aren't the most important things. We need happiness, too."

    The man must care too much about music to buy a radio instead of food clothes. I soon realized(意识到) that happiness is the key to life. Without it, there's nothing to look forward to.

    Since then I've never gone a day without thinking of what's truly important. A home, a meal, clothes—these things are only part of the picture. What's often forgotten is that we all need a pleasure, a light in a dark day. We all need a passion.