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. A is true but R is false.
B. Both A and R are true but R is NOT the correct explanation of A.
C. Both A and R are true and R is the correct explanation of A.
D. A is false but R is true.
Answer: Option C
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:
Nickel (finely divided) catalyzes the addition of hydrogen to unsaturated vegetable oils to form solid vanaspati ghee. It provides surface for reaction. Platinum and palladium also work but are expensive. Iron is used in Haber process. V₂O₅ in Contact process.
Explanation:
According to the reactivity series, zinc is more reactive than copper, so Zn displaces Cu: Zn + CuSO₄ → ZnSO₄ + Cu. Silver, gold, and mercury are less reactive than copper and cannot displace it. Reactivity: K > Na > Ca > Mg > Al > Zn > Fe > Pb > Cu > Ag > Au. Displacement reactions are used in metallurgy and galvanic cells. The blue color of CuSO₄ fades as copper is deposited.
No comments yet. Be the first to start the discussion!