Which of the following statements about a catalyst is incorrect?
A. It remains unchanged in mass after the reaction.
B. It initiates the reaction.
C. It lowers the activation energy.
D. It does not change the enthalpy of the reaction.
Answer: Option B
Solution (By JKExamLibrary)
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:
Nuclear fission is a reaction in which the nucleus of a heavy atom (like Uranium-235 or Plutonium-239) splits into two or smaller, lighter nuclei when bombarded by a neutron, releasing a massive amount of energy and more neutrons, potentially causing a chain reaction.
Explanation:
Ammonium chloride (NH4Cl) consists of the ammonium ion (NH4+) and the chloride ion (Cl-). The bond between NH4+ and Cl- is ionic. However, within the ammonium ion itself, the nitrogen atom is bonded to four hydrogen atoms via covalent bonds (three normal and one coordinate). Thus, it contains both.
Explanation:
Natural rubber (cis-1,4-polyisoprene) is an addition polymer of isoprene (2-methyl-1,3-butadiene). It is obtained from latex of rubber tree (Hevea brasiliensis). It is elastic but weak. Vulcanization with sulfur introduces cross-links, improving strength and elasticity. Ethene gives polyethylene; styrene gives polystyrene; vinyl chloride gives PVC.
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