The element with the largest atomic radius in period 3 is:
A. Cl
B. Ar
C. Mg
D. Na
Answer: Option D
Solution (By JKSSB Mock Tests)
Atomic radius decreases across a period due to increasing nuclear charge. Sodium (Na) is the first element in period 3, thus it has the largest atomic radius. Argon (noble gas) has the smallest (though noble gas radii are van der Waals and larger than covalent, but still trend is decreasing). For metals, Na > Mg > Al; non-metals further smaller.
Explanation:
Uranium (U) is a naturally occurring heavy metal that is radioactive. Its most common isotopes are U-238 and U-235. Aluminum, iron, and calcium are stable, non-radioactive elements under normal conditions, though they may have synthetic radioactive isotopes.
Explanation:
Oxidation is the gain of oxygen or loss of electrons. Here, Carbon (C) gains oxygen to form Carbon dioxide (CO₂), so Carbon is oxidized. Lead oxide (PbO) loses oxygen to form Lead (Pb), so PbO is reduced. This is a classic redox reaction where both processes occur simultaneously.
Explanation:
Using Boyle's law: P₁V₁ = P₂V₂ => 2 atm × 5 L = 1 atm × V₂ => V₂ = 10 L. As pressure decreases, volume increases. The same mass of gas expands. This is a direct application of inverse proportionality. If temperature and amount of gas are constant, doubling pressure halves volume, etc.
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