Assertion (A): Dry HCl gas does not change the color of dry litmus paper. Reason (R): Acids produce H⁺ ions only in the presence of water. MCQ with Answer and Explanation
Assertion (A): Dry HCl gas does not change the color of dry litmus paper. Reason (R): Acids produce H⁺ ions only in the presence of water.
A. Both A and R are true and R is the correct explanation of A.
B. A is true but R is false.
C. Both A and R are true but R is NOT the correct explanation of A.
D. A is false but R is true.
Answer: Option A
Solution (By JKExamLibrary)
The acidic behavior of HCl is due to the presence of H⁺ (or H₃O⁺) ions, which are generated only when it dissolves in water. Without moisture, HCl doesn't dissociate to produce H⁺, so it doesn't change the color of dry litmus. Both statements are correct and R explains A.
Explanation:
Atomic radius decreases across a period because the effective nuclear charge increases while electrons are added to the same shell, pulling the electron cloud closer. Down a group, radius increases due to addition of new shells.
Explanation:
Fe in FeCl₃ goes from +3 to +2 in FeCl₂, gaining an electron – reduction. Sn in SnCl₂ goes from +2 to +4 in SnCl₄, losing electrons – oxidation. FeCl₃ is the oxidizing agent, SnCl₂ is the reducing agent.
Explanation:
Enzymes are complex organic molecules that act as biological catalysts in living organisms. Chemically, most enzymes are globular proteins. They are highly specific to their substrates and work optimally at body temperature and near-neutral pH, unlike many industrial catalysts that require extreme conditions.
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