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为了测定铅的比热容，把质量为200g的铅块加热到98℃，再投入到80g的12℃的水中，混合后水的温度为18℃．若不计热损失，求：

（1）水吸收的热量

（2）铅的比热容．

答案

（1）水吸收的热量：

Q吸=c水m水（t-t0水）

=4.2×103J/（kg•℃）×0.08kg×（18℃-12℃）

=2.016×103J；

（2）∵不计热损失，Q吸=Q放，

∴铅的比热容：

c铅=

Q吸
m铅(t0铅-t铅)
=
2.016×103J
0.2kg×(98℃-18℃)
=126J/（kg•℃）．

答：（1）水吸收的热量为2.016×103J；

（2）铅的比热容是126J/（kg•℃）．

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Frank Adwood, CFA, is the chief compliance officer for Nills Investment Limited. Frank institutes a new policy requiring the pro rata distribution of new security issues to all discretionary accounts for which the new issues are appropriate. The policy does not provide for the distribution of new issues to non-discretionary accounts, but this is disclosed to all existing and potential clients. Did Frank most likely violate any CFA Institute Standards of Professional Conduct（）

A. No.

B. Yes, because the distribution policy fails to treat all discretionary accounts equally.

C. Yes, because disclosure of inequitable allocation methods does not fulfill the duty for fail and equitable trade allocation procedures.
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B.达到k值时种群增长率为零

C.种群增长受自身密度的影响

D.种群的增长速度逐步降低
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