Which of the following elements has the smallest atomic radius in Group 1?
A. Potassium
B. Sodium
C. Lithium
D. Cesium
Answer: Option C
Solution (By JKExamLibrary)
Atomic radius increases down a group due to addition of shells. Lithium (Z=3, 2 shells) is the first element in Group 1 and has the smallest radius. Cesium has the largest. The effective nuclear charge also plays a role, but shell number dominates. Trend: Li < Na < K < Rb < Cs.
Explanation:
In PCl₅, phosphorus forms five covalent bonds with five chlorine atoms. Phosphorus has 5 valence electrons (3s²3p³), and by using d-orbitals, it can expand its octet to accommodate 5 bonds. Thus its covalency is 5. In PCl₃, it is 3. Valency is the number of bonds formed. The oxidation state of P in PCl₅ is +5.
Explanation:
CaO is an ionic compound: Ca loses 2 electrons to form Ca²⁺, O gains 2 electrons to form O²⁻. CH₄, CCl₄, NH₃ are covalent molecules where electrons are shared. Electrovalent compounds are formed between metals and non-metals with a large electronegativity difference.
Explanation:
In any electrochemical cell, the anode is defined as the electrode where oxidation (loss of electrons) takes place, and the cathode is where reduction (gain of electrons) occurs. In an electrolytic cell, the anode is positively charged, attracting anions which then lose electrons.
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