A solution turns red litmus blue. Its pH is likely:
A. 9
B. 2
C. 5
D. 7
Answer: Option A
Solution (By JKExamLibrary)
A solution turning red litmus blue is basic, so pH > 7. Among options, pH 9 is basic. pH 2 and 5 are acidic (blue litmus turns red). pH 7 is neutral. Litmus is a natural indicator extracted from lichens. Red litmus in base remains blue, blue litmus in acid turns red. Practical: Phenolphthalein gives pink in basic solution (pH > 8.3).
Explanation:
Plaster of Paris is CaSO₄·½H₂O. It is made by heating gypsum (CaSO₄·2H₂O) at 373 K. It sets with water to form gypsum again. Used for plastering fractured bones, making statues.
Explanation:
Half-life (t₁/₂) is the time taken for half of the radioactive nuclei in a sample to decay. It is constant for a given isotope and independent of initial amount (first-order kinetics). After one half-life, 50% remains; after two, 25%. It is a measure of stability. Short half-life = more radioactive.
Explanation:
The Contact process is used for the industrial manufacture of sulfuric acid. The key step is the oxidation of sulfur dioxide (SO2) to sulfur trioxide (SO3). This reaction is catalyzed by Vanadium pentoxide (V2O5). Platinum was historically used but was replaced by V2O5 because it is cheaper and less susceptible to poisoning.
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