Which of the following statements about a catalyst is incorrect?
A. It initiates the reaction.
B. It remains unchanged in mass after the reaction.
C. It lowers the activation energy.
D. It does not change the enthalpy of the reaction.
Answer: Option A
Solution (By JKSSB Mock Tests)
A catalyst does not initiate a reaction; it only changes the rate of a reaction that is already thermodynamically feasible. It provides an alternative pathway with lower activation energy. It does not change the overall enthalpy (ΔH) or the equilibrium position, and it is recovered unchanged in mass.
Explanation:
Fractional distillation is the primary separation method in a petroleum refinery, where crude oil is heated and components separated based on boiling points. Cracking breaks larger molecules into smaller ones. Refining includes many processes including distillation. Polymerisation is joining molecules. Fractional distillation yields petrol, kerosene, diesel, etc.
Explanation:
Baking soda is sodium hydrogen carbonate (NaHCO₃). It is used as a leavening agent in baking (produces CO₂ upon heating or with acid), as an antacid, and in fire extinguishers. Sodium carbonate (Na₂CO₃) is washing soda. Calcium carbonate is limestone/marble. Potassium carbonate is potash. Baking powder is a mixture of NaHCO₃ and a weak acid like tartaric acid.
Explanation:
Mass number (A) = protons (Z) + neutrons (N). So Z = A - N = 31 - 16 = 15. This is phosphorus (P). Atomic number 15, mass number 31. It has 15 protons and 15 electrons. Number of neutrons = 16. Isotope notation: ³¹₁₅P.
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