Assertion: HCl gas does not change the colour of dry blue litmus paper...
Assertion:
"HCl gas does not change the colour of dry blue litmus paper."
- This statement is true. Dry HCl gas cannot release hydrogen ions (H⁺) because it needs to be dissolved in water to form hydronium ions (H3O+H_3O^+H3O+), which cause the acidic effect. Therefore, HCl gas will not change the colour of dry blue litmus paper.
Reason:
"HCl gas dissolves in the water present in wet litmus paper to form H⁺ ions."
- This statement is also true. When HCl gas dissolves in the water present on wet litmus paper, it dissociates to form H⁺ ions, which can then change the colour of blue litmus to red, indicating an acidic environment.
Conclusion:
Both the assertion and reason are true, and the reason correctly explains the assertion.
Thus, the correct answer is:
Option 1: Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
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Assertion: HCl gas does not change the colour of dry blue litmus paper...
Assertion and Reasoning
Assertion: HCl gas does not change the colour of dry blue litmus paper.
Reason: HCl gas dissolves in the water present in wet litmus paper to form H+ ions.
Explanation
The assertion is true because dry litmus paper cannot react with HCl gas because it lacks the moisture required for the reaction. HCl gas is not able to dissolve in a dry litmus paper because it requires water to form H+ ions. Therefore, HCl gas does not change the colour of dry blue litmus paper.
The reasoning is also true because HCl gas readily dissolves in water to form H+ ions. When blue litmus paper is wet, it contains water molecules that react with HCl gas to form H+ ions. These ions then react with the litmus paper to change its colour from blue to red.
Conclusion
Both the assertion and the reasoning are true, but the reasoning does not provide a complete explanation for the assertion. The assertion is true because dry litmus paper cannot react with HCl gas, but the reasoning explains how HCl gas reacts when it is in contact with wet litmus paper. Therefore, option A is the correct answer.
Assertion: HCl gas does not change the colour of dry blue litmus paper...
Dry HCl does not change the colour of the dry litmus paper. To show the acidic properties of a particular acid,water need to be added and that is the reason wet litmus changes the colour.
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