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 but R is NOT the correct explanation of A.
B. A is false but R is true.
C. A is true but R is false.
D. Both A and R are true and R is the correct explanation of A.
Answer: Option D
Solution (By JKSSB Mock Tests)
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:
Ethanol (CH₃CH₂OH) and dimethyl ether (CH₃OCH₃) have the same molecular formula C₂H₆O but different functional groups: alcohol (-OH) vs ether (-O-). This is functional group isomerism. Ethanal is C₂H₄O, acetic acid C₂H₄O₂. Methoxymethane is another name for dimethyl ether. Functional isomers exhibit different chemical properties; ethanol reacts with Na, ether does not.
Explanation:
Boyle's law states that at constant temperature, the volume of a given mass of gas is inversely proportional to pressure: PV = constant. So P ∝ 1/V. Charles' law relates V and T at constant P. Gay-Lussac's law relates P and T at constant V. Boyle's law is used in syringes and scuba diving. Graph of P vs V is a hyperbola; P vs 1/V is a straight line.
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