BSc First Year (Sem 1 & 2) Chemistry – Daily Revision MCQ (English Medium)
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Which element has the highest electronegativity on the Pauling scale?
Chapter 2: Periodic Properties
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Answer: A. Fluorine
Fluorine is the most electronegative element (Pauling value about 4.0) because of its small size and high effective nuclear charge.Water (H₂O) is a liquid at room temperature, while H₂S is a gas. The main reason is:
Chapter 4: Metallic Bonding and Hydrogen Bonding
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Answer: C. Intermolecular hydrogen bonding in H₂O
Highly electronegative oxygen lets water molecules form intermolecular hydrogen bonds; sulphur cannot, so H₂S molecules separate easily and it is a gas.Lithium shows a diagonal relationship with which element?
Chapter 5: s-Block and p-Block Elements
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Answer: B. Magnesium
Lithium (group 1, period 2) resembles magnesium (group 2, period 3), the element diagonally below-right of it, because of similar ionic size and polarising power.How many three-centre two-electron (banana) bonds are present in a diborane (B₂H₆) molecule?
Chapter 6: Compounds of p-Block Elements
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Answer: D. Two
Diborane has four terminal B–H bonds and two bridging B–H–B bonds; each bridge is a three-centre two-electron (banana) bond.Which of the following carbocations is the most stable?
Chapter 8: Basic Concepts of Organic Chemistry
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Answer: C. (CH₃)₃C⁺
Stability order is 3° > 2° > 1° > methyl; the tertiary (CH₃)₃C⁺ is stabilised most by the +I effect and hyperconjugation of three methyl groups.An SN2 reaction at a chiral carbon gives a product with:
Chapter 12: Alkyl and Aryl Halides
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Answer: B. inversion of configuration
In SN2 the nucleophile attacks from the side opposite the leaving group in one step, so the configuration is inverted (Walden inversion).In the Lucas test (conc. HCl + anhydrous ZnCl₂), which type of alcohol gives turbidity immediately at room temperature?
Chapter 13: Alcohols, Phenols and Ethers
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Answer: D. Tertiary alcohol
Tertiary alcohols form a stable 3° carbocation fastest, so the insoluble alkyl chloride appears at once; secondary takes a few minutes and primary shows no turbidity at room temperature.The Hell–Volhard–Zelinsky (HVZ) reaction converts a carboxylic acid (with an α-hydrogen), using Br₂ and red phosphorus, into:
Chapter 15: Carboxylic Acids and Their Derivatives
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Answer: A. an α-bromo carboxylic acid
In the HVZ reaction, Br₂ with red P replaces an α-hydrogen of the acid by bromine, giving the α-bromo acid.In the van der Waals equation for real gases, the constant 'a' is a correction for:
Chapter 16: Gaseous State
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Answer: C. the attractive forces between gas molecules
'a' corrects the pressure term for intermolecular attraction; 'b' corrects the volume for the space occupied by the molecules.What happens to the surface tension of a liquid when its temperature is increased?
Chapter 17: Liquid State
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Answer: B. It decreases
Higher temperature raises the kinetic energy of molecules and weakens the net intermolecular pull at the surface, so surface tension decreases.
BSc First Year (Sem 1 & 2): MCQ in other subjects
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All questions are written by PadhaiNotes in our own words from the common syllabus of Maharashtra universities (NEP). Your own university's syllabus may differ a little.