Which of these expressions correctly expresses the solubility-product constant for Ag2CrO4 in water? ( )
A. [Ag+][CrO42-]
B. [Ag+]2[CrO42-]
C. [Ag+][CrO42-]2
D. [Ag+]2[CrO42-]2
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Which solution is the buffer solution? ()
A. HCl
B. H2O
C. NH4Ac
D. HCN-NaCN
Which one is extensive property? ( )
A. bp
B. density
C. color
D. mass
For a close system, which of the following statement is correct? ( )
A. matter can exchange
B. energy can exchange
C. energy cannot exchange
D. nothing can exchange
The formula of the first law of thermodynamics is ( ).
A. ∆U=Q-W
B. ∆U=W-Q
C. ∆U=Q+W
D. ∆Q=U+W
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