Chemistry : One Liner for all competitive Exam 2025

Chemistry: One Liner for all competitive exams 2025. Compiled from different websites for consolidated last-minute revision for all Competitive examinations

Chemistry-Set 1

• Which methods can be used for separating a mixture of NaCl and NH4Cl – Sublimation
• Name the sodium compound which is used to permanently remove the hardness of water       –Sodium carbonate
• What is the scale for measuring a hydrogen ion concentration in a solution  –pH scale
• What is another name for calcium oxide – Quick lime
• Name the German chemist who grouped elements into triads in 1817- Wolfgang Dobereiner
• Which is a property of an ionic compound         – It has a high melting point and boiling point
• Which elements is a liquid at room temperature           -Mercury & Bromine 
• Which is an ester     -CH3COOC2H5
• The Modern Periodic Table based on   Atomic Number   of the elements
• What element is a greenish yellow gas with a characteristic smell at room temperature -Chlorine
• Silver ornaments become black after some time when exposed to air because – Silver reacts with sulphur in the air to form silver sulphide
• The four essential requirements for photosynthesis include- Chlorophyll, sunlight, carbon dioxide and water
• What is the mineral name of rock salt     – Halite
• The chemical name of blue vitriol is        – Copper sulphate
• Which scientist invented the periodic table        -Dmirtri Mendeleev
• Which  air pollutants is known as soot     –Particulate matter
• The chemical composition of the ruby gemstone is      –Aluminium oxide
• What is the chemical symbol of Lead      – Pb
• In periodic table as one goes down the group, which property doesn’t change-    Valency.
• The process of forming a thick layer of aluminium oxide on the surface of aluminium so as to protect it from corrosion is called    -Anodising
• The Big Bang theory was propounded by          -George Lamaitre
• The process of browning of paper in old books is known as       -Foxing
• Name the gas which is filled in wick-type lighters         – Butane
• Chlorophyll contains which element        – Magnesium
• The amount of radiation being emitted by a radioactive material is measured using the conventional unit –           Curie

• Muscovite , pegmatite and biotitie are ores of    – Mica
• Zinc sulfate heptahydrate (ZnSO4.7H2O) is commonly known as                – White viriol         
• Which acid is used in the anodizing process      –Dilute sulphuric acid
• Diamonds can be synthesized by subjecting pure carbon to       – Very high pressure and high temperature
• Chlorine gas, released from chloroflurocarbons, is harmful to the ozone layer  
• The number of valence electrons in a graphite atom is           – four
• The best method to dispose of biological wastes from hospitals is – Incineration
• How many neutrons are present in protium       – 0
• The full form LPG is – Liquified Petroleum Gas
• Which in the air turns silver articles black (when exposed to air)  -Sulphur
• Which gas is found in soda water            – Carbon dioxide
• The compound of a metal found in nature is called       –Mineral
• Settling down of heavier insoluble components of a mixture of water and insoluble substances is called –  sedimentation
• Name the scientist who proposed that electrons are embedded in a positive sphere     – JJ Thomson
• Which elements is a versatile element that forms the basis for all living organisms and many of the things we use     -Carbon
• Which can be used for purification of water       -Alum
• Nylon   is the first synthetic fibre made by man 
• Which organic compounds have suffix ‘al’         -Aldehydes
• What is the atomicity of Phosphorous     –Tetra-atomic
• Which chemicals/gases is/are responsible for causing the greenhouse effect – Water vapour, CO2 and CFCs
• A solution of weak acid and its salt is called       – Buffer solution
• Isotopes are atoms that have the – Same atomic number but different atomic mass
• Which radioisotope is used for the treatment of metastatic bone cancer      –Strontium-89
• If a lit candle is covered with a glass tumbler, the flame gets extinguished after some time. What is the reason for this          – Due to limited oxygen the covered candle got extinguished after some time
• Which polymer is used for the manufacturing of water pipes  -PVC
• What is the IUPAC name of glycerol        – Propane-1,2,3-triol
• What is the ore of aluminium called         –Bauxite

• What is the electronic configuration of rhodium  – 1s2 2s6 2p6 3s2 3p6 3d104s2 4p6 4d8 5s1
• One Carbon credit contains          – 1000 kg of carbon dioxide
• Which noble gas is radioactive in nature            -radon
• Bleaching powder is used for        – Disinfecting water
• Power alcohol is a mixture of        –Petrol and ethyl alcohol
• A flame is made up of three parts: the innermost part and the outermost part. Why is the innermost part black- Because of the presence of un-burnt carbon particles
• Which is the first element on the periodic table – Hydrogen
• Which one is a copper ore            -Malachite
• Which determines that a chemical reaction has not taken place  – Change in size
• What is the melting point of the tungsten filament used in bulbs  –3422o C
• Photosynthesis takes place in the presence of light. Which colour’s light range least affects the rate of Photosynthesis        – Green
• Which metal is used in electroplating on iron to protect it from corrosion and formation of rust       –         Zinc
• Clean development mechanism programme is used to reduce          –Greenhouse gas emission
• Decomposition of calcium carbonate to calcium oxide and carbon dioxide on heating is an example of Thermal decomposition reaction
• Brass is a mixture of – 30% zinc and 70% copper
• The most common isotopes used in a nuclear weapon are of – Uranium and plutonium
• The fibres, such as nylon and polyester, that are made from chemical substances are called      – Synthetic fibres
• Name one alkaline solution – Sodium hydroxide
• Which is the greenish yellow gas with a characteristic smell at room temperature            – Chlorine
• Name one of amphoteric oxide     – Zinc oxide (Examples of amphoteric oxides are zinc oxide and aluminium oxide.) 
• Depending upon carbon and moisture content which is the highest and lowest quality of coal respectively-  Anthracite, lignite
• Ethanol is formed during    – Anaerobic respiration in yeasts
• What do we call a positively charged ion           – cation
• What do we call a negatively charged ion          –anion
• What term is used to denote intermixing of particles of two different types of matter on their own          – Diffusion

• Name the elements that are present in baking powder – Sodium, hydrogen, carbon and oxygen
• Which product is formed due to burning of a magnesium ribbon with a spirit lamp     –         Magnesium oxide
• Name some non-biodegradable materials – Plastic, DDT, Bakelite
• A sucrose molecules contains   12   carbon atoms 
• Fullerene is an allotropic form of   – Carbon
• What is the relative molecular mass of water     – 18 u
• The position of an element in the periodic table is determined by its Proton number
• What is the chemical formula of propane – C3H8
• The natural aging of a lake by nutrient enrichment of its water is termed as – Eutrophication
• To neutralize the effect of formic acid injected by ant bit, which can be used-Sodium bicarbonate
• Synthetic fibres catch fire easily, however, the uniforms of fireman have a coating of   Melamine   plastic to make them flame resistant 
• The term ‘Isotope’ refers to – Elements having same atomic number but different mass number
• Homogenous mixture of a solute and a solvent is called           – Solution
• Which gas can be fixed in the atmosphere by lightning           – Nitrogen
• Which minerals is obtained from veins and lodes – Major metallic minerals like tin, copper, zinc and lead etc. are obtained from veins and lodes.
• What is the average temperature of the surface water of the oceans                         –17 degree Celsius
• The reaction between an acid and a base is known as           –Neutralisation.
• Silver bromide used in       – Black and white Photography
• The process of melting that is change of solid state into liquid state is known as      – Fusion
• State of matter can be changed into another state by changing the – Temperature
• The heat energy required to convert a solid into a liquid or vapour, or a liquid into a vapour, without change of temperature known as – Latent heat
• The unit of pressure is       –Pascal
• A change of state directly from solid to gas without changing into liquid state is called – Sublimation 
• Direct change of gas to solid without changing into liquid is called – Deposition.

• The number of atoms constituting a molecule is known as       – Atomicity.
• Electron was discovered by                    -JJ Thomson
• Proton was discovered by            – Rutherford
• The ratio by number of atoms for water is H:O             – 2:1.
• The ratio of hydrogen and oxygen by mass in water is           –1:8
• Neutrons are present in the nucleus of all atoms, except           –Hydrogen
• Maximum number of electrons present in a shell is given by the formula –2n2
• Who suggested the distribution of electrons into different orbits of an atom –  Bohr and Bury
• The stranger gas is  –Xenon
• Ammonia (NH3) is synthesized through – Haber‘s process
• Egg shell is made up of      – Calcium Carbonate
• Fuse wire is made up of – Lead and Tin
• Acid rain is caused when the air is polluted by   – Nitrous Oxide &Sulphur dioxide 
• Ozone is allotrope of – oxygen
• The chemical that is used in making artificial rain is     – Silver nitrate.
• What is the ratio of HNO3 and HCl in aqua regia         – 1:3
• The hardest substance available on earth is      – Diamond
• The nature of saliva is        – Acidic.
• Bee Sting contains a          – Methanoic Acid
• The impurity present in the ore is called as        – Gangue
• Lightest element in the universe is          – Hydrogen 
• Quicksilver is another name of     – Mercury
• Chemical name of Green vitriol is – Iron sulphate
• Bhopal gas Tragedy of 1984 is related to – Methyl Isocyanate
• The lowest temperature at which a substance catches fire is called its        –Ignition temperature.
• The substances which have very low ignition temperature and can easily catch fire with a flame are called – Inflammable substances
• A chemical process in which a substance reacts with oxygen to give off heat is called – Combustion.
• The amount of heat energy produced on complete combustion of 1 kg of a fuel is called its –         Calorific value.
• Galvanization is a method of protecting steel and iron from rusting by coating them with a thin layer of –          Zinc.
• Hydrogen gas is not evolved when a metal reacts with           – Nitric acid.

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