Which of the following statements about catalysts is correct?
A. They lower the activation energy of the reaction
B. They are always solid
C. They change the equilibrium constant
D. They are consumed in the reaction
Answer: Option A
Solution (By JKExamLibrary)
Catalysts provide an alternative pathway with lower activation energy, increasing reaction rate without being consumed. They do not affect equilibrium constant or thermodynamic parameters (ΔH, ΔS). They can be solid (heterogeneous), liquid, or gas. Enzymes are liquid-phase catalysts. A catalyst does not change the position of equilibrium, only speeds up attainment.
Explanation:
Mercury (Hg) is the only metal that is liquid at room temperature. Gallium and cesium melt slightly above room temperature. Sodium is solid but soft. Zinc and aluminium are solids. Mercury is used in thermometers and barometers.
Explanation:
Green chemistry aims to design products and processes that minimize the use and generation of hazardous substances. Using hydrogen peroxide (H2O2) for bleaching paper is an example of green chemistry because it breaks down into harmless water and oxygen, unlike chlorine which can produce toxic, persistent organochlorine byproducts.
Explanation:
Salivary amylase (ptyalin) hydrolyzes starch into maltose in the mouth. Pepsin digests protein in stomach; lipase digests fats; trypsin is pancreatic enzyme for proteins.
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