Which of the following metals reacts vigorously with cold water?
A. Copper
B. Iron
C. Sodium
D. Zinc
Answer: Option C
Solution (By JKExamLibrary)
Sodium (alkali metal) reacts violently with cold water: 2Na + 2H₂O → 2NaOH + H₂ + heat. Copper and iron do not react with cold water; iron reacts with steam. Zinc also reacts with steam. Reactivity with water increases down Group 1.
Explanation:
Oxidation is defined as the loss of electrons (or an increase in oxidation state). A reducing agent is a substance that donates electrons to another species, thereby causing the other species to be reduced. In doing so, the reducing agent itself gets oxidized. Thus, statement 1 is correct, but 2 is incorrect.
Explanation:
Teflon (PTFE) has low friction and high heat stability, ideal for non-stick coatings. PVC for pipes; polystyrene for packaging; nylon for fibers.
Explanation:
Elements in the same group (vertical column) have the same number of valence electrons, resulting in similar chemical properties. For example, all Group 1 elements have 1 valence electron (ns¹). The number of shells increases down the group. Atomic mass varies. This similarity was the basis for Mendeleev's grouping. Modern table uses atomic number for ordering.
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