Here are 100 important one-word or two-word answer Chemistry questions for UPSC, SSC, Railways, and other competitive exams:
General Chemistry
SI unit of amount of substance?
– Mole
Chemical formula of water?
– H₂O
SI unit of temperature?
– Kelvin
Atom with the smallest atomic number?
– Hydrogen
Heaviest naturally occurring element?
– Uranium
Isotope of Hydrogen?
– Deuterium
Non-metal that is a good conductor of electricity?
– Graphite
Molecule with the highest boiling point?
– Water
First periodic table creator?
– Dmitri Mendeleev
Element with atomic number 1?
– Hydrogen
Atomic Structure
Who discovered the electron?
– J.J. Thomson
Charge of proton?
– Positive
Mass number of an atom?
– Sum of protons and neutrons
Who proposed the planetary model of the atom?
– Niels Bohr
Who discovered the neutron?
– James Chadwick
Bohr’s model is based on?
– Quantum theory
Who discovered the proton?
– Ernest Rutherford
Number of electrons in a neutral atom?
– Equal to protons
Who proposed the electron cloud model?
– Schrodinger
First ionization energy is highest in?
– Helium
Periodic Table
Who discovered noble gases?
– William Ramsay
Element in group 1 of the periodic table?
– Sodium
Element with atomic number 17?
– Chlorine
Element with atomic number 79?
– Gold
Group 2 elements are known as?
– Alkaline Earth Metals
Group 17 elements are known as?
– Halogens
Group 18 elements are known as?
– Noble gases
Element in group 14?
– Carbon
Most reactive non-metal?
– Fluorine
Most reactive metal?
– Cesium
Chemical Bonding
Bond formed by sharing electrons?
– Covalent Bond
Bond formed by electron transfer?
– Ionic Bond
Strongest type of bond?
– Covalent Bond
Molecule with double bonds?
– O₂ (Oxygen)
Bond formed between metals?
– Metallic Bond
Electronegativity trend in periodic table?
– Increases across a period, decreases down a group
Example of ionic compound?
– Sodium Chloride (NaCl)
Molecule with triple bonds?
– N₂ (Nitrogen)
Shape of methane molecule?
– Tetrahedral
Bond between H and Cl in HCl?
– Polar Covalent
States of Matter
Substance with fixed shape and volume?
– Solid
Substance with definite volume but no fixed shape?
– Liquid
Substance with no definite shape or volume?
– Gas
State of matter with highest energy?
– Gas
Process of solid turning into gas?
– Sublimation
Process of liquid turning into gas?
– Evaporation
Process of gas turning into liquid?
– Condensation
What is plasma?
– Ionized gas
Example of solid to liquid process?
– Melting
Critical point refers to?
– Highest temperature and pressure a substance can exist as liquid and gas
Chemical Reactions
Reaction type: AB → A + B?
– Decomposition
Reaction type: A + B → AB?
– Combination
Reaction type: AB + CD → AD + CB?
– Double Displacement
Reaction type: A + B → AB?
– Synthesis
Reaction type: C + O₂ → CO₂?
– Combustion
Catalyst in the Haber process?
– Iron
Reaction involving electron transfer?
– Redox Reaction
Reaction that absorbs heat?
– Endothermic
Reaction that releases heat?
– Exothermic
Energy required to break bonds?
– Bond Dissociation Energy
Solutions and Concentration
Concentration unit for solutions?
– Molarity
Substance that dissolves in a solvent?
– Solute
Substance that does the dissolving?
– Solvent
Unit of concentration in terms of mass?
– Molality
Formula for molarity?
– M = moles of solute/volume of solution
Solvent in water-based solutions?
– Water
A solution that cannot dissolve more solute?
– Saturated
A solution that can dissolve more solute?
– Unsaturated
Process of solute leaving the solution?
– Crystallization
Colloid example?
– Milk
Acids, Bases, and pH
pH of neutral water?
– 7
Acid with a sour taste?
– Citric Acid
Base used in soap?
– Sodium Hydroxide
Indicator for acids and bases?
– Litmus
pH of hydrochloric acid?
– Less than 7
Alkaline substance?
– Ammonia
Strongest acid?
– Fluoroantimonic acid
Substance that neutralizes acids?
– Base
Salt formed by HCl and NaOH?
– Sodium Chloride (NaCl)
pH of bleach?
– Around 12
Electrochemistry
Device used for electrolysis?
– Electrolytic Cell
Positive electrode in electrolysis?
– Anode
Negative electrode in electrolysis?
– Cathode
Flow of charge in an electrolyte solution?
– Electric Current
Chemical reaction at anode?
– Oxidation
Chemical reaction at cathode?
– Reduction
Battery used in cars?
– Lead-Acid Battery
Electrolyte in a battery?
– Acid or Base
Cell used in a flashlight?
– Dry Cell
Conductivity in ionic compounds?
– Conducts when molten or dissolved
Organic Chemistry
Simplest alkane?
– Methane
Compound with C=C double bond?
– Alkene
Functional group in alcohol?
– Hydroxyl group
Group in aldehyde?
– Carbonyl group
Group in carboxylic acid?
– Carboxyl group
Benzene ring is made of?
– Six carbon atoms
Common plastic made from ethylene?
– Polyethylene
Natural polymer example?
– Starch
Benzene derivative used as a solvent?
– Toluene
Compounds with the same molecular formula but different structures?
– Isomers
