Which metal is most reactive according to the reactivity series?
A. Cu
B. Fe
C. Zn
D. K
Answer: Option D
Solution (By JKExamLibrary)
Potassium (K) is at the top of the reactivity series, meaning it is the most reactive among the given metals. The order of reactivity (decreasing): K > Na > Ca > Mg > Al > Zn > Fe > Pb > Cu > Ag > Au. Potassium reacts violently with water and oxygen. Copper (Cu) is relatively unreactive and is found native in nature. Exam trick: Remember 'Please Stop Calling Me A Cute Zebra...' mnemonic.
Explanation:
Chlorine leaves a residual in water, continuing to protect against recontamination in distribution pipes. Ozone and UV kill instantly but do not provide residual disinfection. Boiling is not used for municipal supply.
Explanation:
Mg + 2HCl → MgCl₂ + H₂↑. Magnesium displaces hydrogen from acid. This is a single displacement and redox reaction. Copper does not react similarly.
Explanation:
Hydrogenation is the addition of hydrogen to unsaturated compounds (like alkenes or alkynes) in the presence of a catalyst (like Ni, Pd, or Pt) to form saturated compounds (alkanes). For example, ethene + H₂ → ethane. This process is widely used in the food industry to solidify vegetable oils.
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