人体血液中平均每1000ml中含190mg K+,则血液中K+的浓度是( )
A. 0.49mol/L
B. 4.9×10-3mol/L
C. 4.9×10-4mol/L
D. 4.9×10-2 mol/L
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硫酸试剂瓶上的标记是:H2SO4的ωB=0.80密度为1.727g/ml,相对分子至98.00。该酸的物质的量浓度是( )
A. 10.2mol/L
B. 14.1mol/L
C. 14.1mol/kg
D. 16.6 mol/L
用18 mol/L的浓H2SO4 4.5 ml配成450 ml的溶液,该溶液的物质的量浓度是( )
A. 0.25mol/L
B. 0.28mol/L
C. 0.18 mol/L
D. 0.35mol/L
1L含甘油46.0g的水溶液在27℃时的渗透压是M(甘油)=92.00g/mol
A. 112kPa
B. 1.13×103kPa
C. 1.25×103kPa
D. 2.49×103kPa
[音频]Friendship can be confusing to young adults at times, especially when it comes to friendship with the opposite sex. Now listen to a passage and complete the following outline with what you hear.Can men and women be just friends?Research 1Number of subjects: 1) ___________ of friends of the opposite sexMethod: Each pair of friends were separated and each member was askedquestions about his or her 2) _____________ toward the otherone.Findings: 1 Men were more likely to 3) ___________ their female friends,and they tended to believe that their female friends felt thesame way.Findings: 2 Women were generally 4) __________ to the men and theybelieved their male friends also felt the same way.3 When a female friend was in love with someone else, men werestill likely to 5) ___________ romantic dates with her.4 Women were sensitive to their male friends’ relationship andshowed 6) ___________ in those already in love.Research 2Number of subjects: 7) ___________ adultsMethod: List the positive and negative 8) ___________ of friendships withthe opposite sex.Findings: 1 Males were much more likely than females to list romance as a9) ___________.2 This difference between men and women seemed to be even10) ___________ among older people.