题干

把500mLNH4HCO3和Na2CO3的混合溶液分成5等份,取一份加入含amolNaOH的溶液恰好反应完全;另一份加入含bmolHCl的盐酸溶液恰好反应完全,则该混合溶液中c(Na+)为

A:

B:(2b-a)mol/L

C:

D:(10b-5a)mol/L

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答案(点此获取答案解析)

D

同类题2

阅读下列短文,从下面每小题的A、B、C、D四个选项中选出最佳选项。

Passage 1

2017-May-10 Shenzhen Daily

     A boy and his mother picked rubbish in Niushan Park, Guangming New Area. A number of children, led by their parents, took part in an environmental protection activity. The children picked rubbish, and learned knowledge about garbage classification. More similar activities will be organized in the coming months to let them know the importance of environmental protection.

Passage 2

2017-May-11 Shenzhen Daily

A man was knocked down by a car and died when he crossed Shahe East Road in Nanshan District by bike. This is the second accident about unruly bike riders since April 30. Another one is: a woman rode a bike against traffic in a motor lane and was hit by a bus in Luohu District on April 30. She died at once.

Passage 3

2017-May-12 Shenzhen Daily

The number of registered app-bike users in Shenzhen reached 10.52 million at the end of March. The seven bike operators in the city had offered 2.59 million rides a day on the 530,000 bicycles across the city. Among the users, around one-quarter used bikes more than six times a week and the other one-third used bikes between 3 and 5 times a week. 29 percent used them for sports and fitness and 12 percent used them for entertainment and shopping.

Passage 4

2017-May-12 Beijing Youth Daily

Beijing plans to recruit (招募) 30 junior high school students and train them to repair cultural relics (遗产) for the Forbidden City according to Beijing Youth Daily.

     They will study cultural relic rebuilding at the Beijing International Vocational Education School for three years. Besides general courses including Chinese, math and politics, the students also learn about relic repair, including basic knowledge of cultural relics, the history of arts and the basic methods of relic protection.