✔ 最佳答案
The answer is C.
(1) is correct.
Na2CO3(s) + H2SO4(aq) → Na2SO4(aq) + H2O(l)
(2) is incorrect.
CaCO3(s) + H2SO4(aq) → CaSO4(s) + H2O(l)
CaSO4 is only slightly soluble in water, which will thus form a solid layer on the surface of the CaCO3 reactant. The solid layer of CaSO4 separate the CaCO3 and the H2SO4 to stop the reaction soon after the reaction starts. Therefore, the reaction would not be completed.
(3) is correct.
MgCO3(s) + H2SO4(aq) → MgSO4(aq) + H2O(l)
(Since both Na2SO4 and MgSO4 are soluble in water, reactions (1) and (3) can go complete.)
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The answer is C.
After ten hours, there is no observable change. The hydrogen and water remain unchanged.
A is incorrect.
An experiment without observable change cannot be used to demonstrate the occurrence of a reaction.
B is incorrect.
This is because there is no decrease in the volume of hydrogen.
C is correct.
This is because there is no change in the volume of hydrogen.
D is incorrect.
This is because there is no increase in the volume of hydrogen.
