Which property increases down a group? MCQ with Answer and Explanation

Explanation:
Red litmus turning blue indicates that the solution is basic. Basic solutions have a pH greater than 7. Among the options, 10 is the only value greater than 7. pH 1 and 4 are acidic (turn blue litmus red), and 7 is neutral (no change in litmus color).

Explanation:
A positive catalyst increases reaction rate by lowering activation energy. Decreasing temperature generally slows reactions. Decreasing concentration reduces collision frequency, lowering rate. Larger pieces have less surface area, slower reaction. Other rate-increasing factors: increasing temperature, increasing pressure (for gases), using finely powdered solids, and light for photochemical reactions.

Explanation:
Aqua regia (royal water) is a 3:1 mixture of concentrated HCl and HNO₃. It can dissolve noble metals gold and platinum by forming complex ions. Freshly prepared, it is a fuming yellow liquid. Used in etching and cleaning.