Dogs are too _____ to take care of.
A:difficult
B:more difficult
C:most difficult
D:the most difficult
①同温、同压下,相同体积的氟气和氩气所含的原子数相等
②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NA
③在标准状况下,22.4L H2O的物质的量为1mol
④4℃时5.4mL的水所含的原子总数为0.9NA
⑤0.1molOH﹣含0.1NA个电子.
实验一: