IGCSE Chemistry: Specimen Questions with Answers 29 - 31 of 240
Question number: 29
Question
Presence of Hydroxide ions in a solution suggests the presence of ________ in the solution.
Choices
| Choice (4) | Response | |
|---|---|---|
| a. | Acid |
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| b. | Salt |
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| c. | Base |
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| d. | Question does not provide sufficient data or is vague |
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Answer
c.Explanation
Presence of Hydroxide ions in a solution suggests the presence of base in the solution. ions indicate the presence of base.
Question number: 30
Question
The diagram shows an experiment.
Images of Experiment
Images of experiment
Choices
| Choice (4) | Response | |
|---|---|---|
| a. |  Image for Pieces of Litmus Paper: Choice A Image for pieces of litmus paper |
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| b. |  Image for Pieces of Litmus Paper: Choice B Image for pieces of litmus paper |
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| c. |  Image for Pieces of Litmus Paper: Choice C Image for pieces of litmus paper |
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| d. |  Image for Pieces of Litmus Paper: Choice D Image for pieces of litmus paper |
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Answer
c.Explanation
Correct option is C because when we react with it gives as shown in figure. is basic while is neutral so whole solution is basic. Under basic solution Blue litmus is no color change and red litmus is changes its color to blue.
Image for Formation of Ammonia
Image for Formation of Ammonia
Question number: 31
Write in Short
Aluminum and gallium are in Group III of the Periodic Table.
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The heat from your hand is sufficient to melt gallium.
Describe the change in state from solid to liquid in terms of the kinetic particle theory. In your answer include
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the difference in arrangement and closeness of the particles in a solid and a liquid,
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the difference in the motion of the particles in a solid and a liquid.
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Explanation
Elemental gallium is a soft, silvery blue metal at standard temperature and pressure, a brittle solid at low temperatures, and a liquid at temperatures greater than (above room temperature, but below the normal human body temperature). The melting point of gallium is used as a temperature reference point. So the gallium become liquid when comes in contact of human body. The kinetic human theory is given by diagram.
The Kinetic Human Theory
The kinetic human theory