Which of the following is the correct order of atomic radius?
Answer: B
Atomic radius increases down a group in the periodic table. As we go from Na to K to Rb to Cs, the number of shells increases, leading to increased atomic radius.
Q.2Easy
Which of the following elements forms the most stable hydride?
Answer: B
Fluorine forms HF which is the most stable hydride among halogens due to the strong H-F bond (high bond energy ~570 kJ/mol), resulting from fluorine's high electronegativity.
Q.3Easy
Which of the following oxides is amphoteric?
Answer: B
Al₂O₃ is amphoteric, reacting with both strong acids (forming AlCl₃) and strong bases (forming aluminate ions). Na₂O is basic, SiO₂ is acidic, and P₂O₅ is acidic.
Q.4Easy
Which of the following has the highest electronegativity value?
Answer: B
Fluorine has the highest electronegativity value (4.0 on Pauling scale) among all elements due to its small size and high nuclear charge.
Q.5Easy
Which statement about nitrogen oxides is incorrect?
Answer: C
N₂O₄ is colorless gas, not blue. NO is colorless, NO₂ is brown/reddish-brown, and N₂O is indeed called laughing gas.
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Q.6Easy
Which of the following is not a property of noble gases?
Answer: A
Noble gases have VERY HIGH ionization energies (not low) due to their stable electron configuration. All other options are correct properties of noble gases.
Q.7Easy
The coordination number of Cu²⁺ in CuSO₄·5H₂O is:
Answer: B
Cu²⁺ is surrounded by 4 water molecules in the coordination sphere and 2 more from the sulfate ion or additional water molecules, giving octahedral geometry with coordination number 6.
Q.8Easy
Which of the following d-block elements has the configuration [Ar]3d¹⁰4s¹?
Answer: A
Copper has atomic number 29 with configuration [Ar]3d¹⁰4s¹. It exhibits anomalous behavior by having a completely filled d-orbital.
Q.9Easy
The hybridization of sulfur in SF₆ molecule is:
Answer: C
SF₆ has 6 bonding pairs around sulfur with no lone pairs, requiring sp³d² hybridization for octahedral geometry.
Q.10Easy
The bond angle in PCl₃ is approximately:
Answer: B
PCl₃ has trigonal pyramidal geometry with one lone pair on phosphorus. Bond angle is approximately 107° due to lone pair repulsion.
Q.11Easy
The oxidation state of Mn in KMnO₄ is:
Answer: C
In KMnO₄, K is +1, O is -2, so Mn is +7. This makes permanganate a strong oxidizing agent.
Q.12Easy
In the thermite reaction, which metal is oxidized?
Answer: C
In the thermite reaction (2Al + Fe₂O₃ → Al₂O₃ + 2Fe), aluminum is oxidized from 0 to +3 oxidation state as it reduces Fe₂O₃.
Q.13Easy
What is the coordination number of zinc in [Zn(CN)₄]²⁻?
Answer: B
Zinc has a coordination number of 4 in this complex as four cyanide ligands are bonded to it. This follows the typical tetrahedral geometry for Zn²⁺.
Q.14Easy
Which metal exhibits variable oxidation states primarily due to incomplete d-orbital filling?
Answer: B
Iron (Fe) exhibits variable oxidation states (+2 and +3) due to its incomplete d-orbitals, allowing electron transitions between different oxidation states.
Q.15Easy
The white precipitate formed when AgNO₃ is added to a solution containing Cl⁻ ions is:
Answer: B
AgCl is a white precipitate (Ksp = 1.8 × 10⁻¹⁰) formed due to the low solubility product of silver chloride.
Q.16Easy
The ionization energy generally increases across a period because:
Answer: B
Across a period, increasing nuclear charge more significantly affects ionization energy than the slight increase in shielding, causing IE to increase.
Q.17Easy
Which halogen has the lowest electronegativity?
Answer: D
Iodine has the lowest electronegativity among halogens (2.5) due to its largest atomic radius and furthest valence electrons from nucleus.
Q.18Easy
Which of the following compounds would exhibit hydrogen bonding?
Answer: B
HF exhibits hydrogen bonding between H (bonded to highly electronegative F) and lone pairs on F of adjacent molecules.
Q.19Easy
Which of the following d-block elements has the configuration [Ar]3d⁵4s¹?
Answer: A
Chromium has the electronic configuration [Ar]3d⁵4s¹ due to half-filled d-orbital stability, making it more stable than [Ar]3d⁴4s².
Q.20Easy
Among the following oxides, which one is amphoteric?
Answer: B
Al₂O₃ reacts with both strong acids and strong bases, exhibiting amphoteric character. MgO is basic, Na₂O is strongly basic, and Cl₂O₇ is acidic.
