Passage IV
When 2 aqueous (water-based) solutions are mixed together, a chemical reaction between the substances dissolved in the solutions may take place. Evidence of a chemical reaction includes one or more of the following:
formation of a precipitate (ppt, a solid)
release of heat to the solution (solution gets hotter)
absorption of heat from the solution (solution gets colder)
release of a gas (indicated by the formation of bubbles or by an odor)
The table below shows what was observed when various aqueous solutions were mixed.
Table adapted from J. Dudley et al., Health Chemistry—Teacher's Annotated Edition. ©1987 by D. C. Health and Company.
21. An aqueous CoSO4 solution was mixed with 1 of the other solutions listed in the table and a red solid formed. A chemist claimed that the other solution must have contained K2CO3. Based on the table, is his claim valid?
Your Answer is
Correct Answer is A
Explanation
According to the chart, it can be seen that CoSO4 will produce red ppt when encountering K2CO3 or NaOH, so It is incorrect to say that the other reactant must contain K2CO3 in the question stem