Alloying iron with chromium and nickel produces stainless steel which is resistant to corrosion because:
A. Iron becomes non-metal
B. Chromium forms a protective oxide layer
C. Chromium makes iron more reactive
D. Nickel dissolves in iron and prevents reaction
Answer: Option B
Solution (By JKSSB Mock Tests)
Stainless steel contains at least 10.5% chromium, which reacts with oxygen to form a thin, adherent, transparent Cr₂O₃ layer (passive film) that prevents further oxidation of the underlying metal. Nickel enhances corrosion resistance and ductility. This self-healing oxide layer makes it 'stainless'. Unlike galvanization, the protection is not sacrificial but barrier-type from the inherent alloy composition.
Explanation:
Chromium (minimum 10.5%) forms a thin, adherent, transparent oxide layer (Cr₂O₃) on the surface, preventing further oxidation. Nickel adds ductility and enhances corrosion resistance. Iron is the base; carbon is for hardness but not corrosion resistance.
Explanation:
Graphite is used in electrodes (due to electrical conductivity) and as a moderator in nuclear reactors (to slow down neutrons). It is chemically stable and can withstand high temperatures. Diamond is an insulator. Fullerene is a nanomaterial. Charcoal is used as adsorbent and fuel. Graphite blocks are used in RBMK reactors (like Chernobyl) and in advanced gas-cooled reactors.
Explanation:
Across period 3, ionization energy increases from Na to Ar. Chlorine has high ionization energy due to high effective nuclear charge and small atomic radius, though Argon is highest. Among these, Cl has highest IE.
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