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【简答题】
阅读理解。 One day, Allan and his friend Henry went swimming in a river. It was very hot. How happy they were in the river! After they got out of the water, they played games in the sun for a while. On their way back, Henry saw some flowers. He liked flowers very much and ran into the green field to look at them. Now Allan was walking by himself. Then he heard Henry calling out, 'A snake (蛇)! Help!...' 'What's wrong with you?' asked Allan. 'A snake bit (咬) me in the leg. Come here!' Allan ran over and saw a small red wound (伤口) on Henry' s leg. 'The snake was in the grass. I didn't see it.' 'Sit down quickly'! Allan told Henry. Allan put his mouth at the little red wound and began to suck (吸) at it. In this way he saved (挽救) Henry's life. 'Oh, Allan, it's very kind of you to help me.' 'That's all right. We are friends and we must always help each other.' 1. It was _______ when-Allan and Henry went out. A. hot B. cold C. raining D. wet 2. After swimming, they played in the sun ________. A. the whole morning B. for 2 hours C. long D. for a while 3. On their way home, ________ got something wrong with his A. Allan; leg B. Allan; head C. Henry; leg D. Henry; head 4. Henry and Allan are ________. A. workers B. good friends C. brothers D. farmers 5. Which of the following (下面的) is true? A. Henry went to look at the flowers with Allan. B. Allan saved Henry' s life. C. Allan saw the snake. D. They ran to the hospital at once.
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【简答题】某无色溶液由石灰水、盐酸、氢氧化钠溶液、氯化钠溶液、碳酸钠溶液中的两种组成。 已知:氯化钙溶液为中性,碳酸钠溶液为碱性,Na 2 CO 3 + CaCl 2 = CaCO 3 ↓ + 2NaCl。 (1)若取适量样品放入试管中,滴加无色酚酞溶液,溶液为无色。溶液的组成是________。 (2)若取适量样品放入试管中,滴加无色酚酞溶液,溶液变成红色,再向试管中加入过量的氢氧化钙溶液,观察到有沉淀产...
【判断题】选区激光烧结成型技术起源于英国
A.
正确
B.
错误
【简答题】常温下某盐酸溶液的pH=2.0,则此溶液中的OH-浓度为__________mol/L;若将此溶液用水稀释至原来浓度的1/10,则稀释后溶液中0H-浓度为__________mol/L。
【单选题】某一元弱酸HA的溶液中,若未电离的HA分子个数与溶液中的离子个数(忽略水电离)比为a:b,则HA的电离度(即转化率)是
A.
×100%
B.
×100%
C.
×100%
D.
×100%
【判断题】玻璃仪器尽可能倒置,高、大的玻璃仪器放在实验柜里面。
A.
正确
B.
错误
【判断题】玻璃仪器尽可能倒置,高、大的仪器放在实验柜里面。
A.
正确
B.
错误
【单选题】某温度下一定量的硝酸钾溶液,若将该溶液恒温蒸发掉 20 g 水,溶液恰好达到饱和状态;若在原溶液中加入 6g 硝酸钾,充分搅拌后,仍有 2 g 不溶解。该温度下硝酸钾的溶解度为
A.
20 g/100 g 水
B.
15 g/100 g 水
C.
10 g/100 g 水
D.
5 g/100 g 水
【单选题】常温下,下列有关溶液的说法不正确的是
A.
某物质的水溶液中由水电离出的c(H + )=1×10 -a mol/L,若a>7,则该溶液的pH为a或14-a
B.
将0.2 mol/L的某一元弱酸HA溶液和0.1mol/L NaOH溶液等体积混合后溶液中存在:2c(OH - )+ c(A - )=2c(H + )+c(HA)
C.
pH=3的二元弱酸H 2 R溶液与 pH=11的NaOH溶液混合后,混合液的pH等于7,则混合液中c(R 2- ) > c(Na + ) > c(HR - )
D.
相同温度下,0.2mol/L的醋酸溶液与0.1mol/L的醋酸溶液中c(H + )之比小于2:1
【单选题】对于某酸的酸式盐NaHY的水溶液的下列叙述中,正确的是(  )
A.
该酸式盐的水溶液一定显酸性
B.
在该盐溶液中,离子浓度为c(Na + )>c(Y 2 - )>c(HY - )>c(OH - )>c(H + )
C.
若HY - 能水解,水解方程式为HY - +H 2 O Y 2 - +H 3 O +
D.
若HY - 能电离,电离方程式为HY - +H 2 O Y 2 - +H 3 O +
【简答题】某一弱酸HA的标准解离常数 在水溶液中的解离度为α。若加等体积水稀释此洛液,则发生的变化是( )。
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