【单选题】There are many older people in the world and there will be many more. A little-known fact is that over 60 percent of the older people live in developing countries. According to the World Health Organi...
A.
is bigger in developed countries than in developing countries
B.
is one-seventh of the population in developing countries
C.
will increase much faster in China than in France
D.
will be sixty percent in developing countries by 2020
【单选题】用N A 表示阿伏加德罗常数,下列说法中正确的组合为 [ ] ①18gD 2 O含有的电子数为10N A ②同温、同压下,相同体积的氟气和氩气所含的原子数相等 ③标准状况下,11.2L以任意比例混合的氮气和氧气所含的原子数为N A ④在标准状况下,22.4LSO 3 的物质的量为1mol ⑤1molNa 2 O 2 含有的离子数为3N A ⑥0.1molOH - 含N A 个电子 ⑦1mo...