IGCSE Chemistry Paper-1: Specimen Questions with Answers 98 - 99 of 99
Question number: 98
Question
Which of the following is a precipitation reaction?
Choices
| Choice (4) | Response | |
|---|---|---|
| a. | AgNO₃+NaCl AgCl + NaNO₃ |
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| b. | Zn + CuSO₄ + ZnSO₄ + Cu |
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| c. | HCl + NaOH NaCl + H₂O |
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| d. | Question does not provide sufficient data or is vague |
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Answer
a.Explanation
A precipitate is a solid that forms out of solution. A common example is that of the mixing of two clear solutions: (1) silver nitrate (AgNO3) and (2) sodium chloride (NaCl): The reaction is.
AgNO₃+NaCl AgCl + NaNO₃
The precipitate forms because the solid (AgCl) is insoluble in water.
Question number: 99
Question
Arrange the following elements in the decreasing order of their metallic character.
Cu, Ag, K, Br, Ca
Choices
| Choice (4) | Response | |
|---|---|---|
| a. | Br > Ag > Cu > K > Ca |
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| b. | Ca > K > Ag > Cu > Br |
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| c. | K > Ca > Ag > Cu > Br |
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| d. | Question does not provide sufficient data or is vague |
|
Answer
c.Explanation
Arranging the elements into different groups and periods:
Arrangement of the Elements K, Ca, Cu, Br and Ag
Arrangement of elements in group and period
Since the metallic character decreases along a period from left to right, therefore, metallic character decreases in the order K > Ca > Cu > Br.
Since metallic character increases down the group from top to bottom, therefore Ag is more metallic then Cu.