Which of the following trends is observed in Group 1 (alkali metals) down the group?
A. Ionization energy increases
B. Electronegativity increases
C. Atomic radius increases
D. Reactivity decreases
Answer: Option C
Solution (By JKSSB Mock Tests)
Down Group 1 (Li → Fr), atomic radius increases due to addition of electron shells. Ionization energy and electronegativity decrease. Reactivity with water increases because the outer electron is more easily lost. Density generally increases, melting/boiling points decrease. Cesium and francium are most reactive. The increase in radius is due to principal quantum number increase.
Explanation:
Graphite, an allotrope of carbon, is a good conductor of electricity. This is because each carbon atom is bonded to three others, leaving one free valence electron per atom that is delocalized and can move freely between the layers to conduct electricity, unlike diamond which is an insulator.
Explanation:
The diagonal relationship occurs when elements in the second period resemble elements in the third period of the next group due to similar ionic sizes and charge-to-radius ratios (polarizing power). Li-Mg, Be-Al, and B-Si are all classic examples of this phenomenon.
Explanation:
Compressed Natural Gas (CNG) is primarily methane (CH₄). It is stored at high pressure (200-250 bar). It is used as a vehicular fuel and for cooking. LPG is primarily propane and butane. CNG is cleaner, produces less CO₂ per unit energy, and is safer in leaks as methane is lighter than air. It has high octane rating.
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