Class 12 Chemistry Most Important Questions 2080 with Free PDF

Chemistry Most Important Questions of Class 12

Class 12 Exams are actually quite tough and pressurizing. Getting good marks or a perfect A+ in Class 12 Exam is even more harder. But with right plan and strategies, students can score best marks and get Perfect GPA in exams. This article exactly tells the students waiting for their exams about 5 tips that actually help them ace in their exam with practical experience.

The questions asked in chemistry board exams are mainly covered in a porportionate ratio from all sections. Specially, the sections of class 12 chemistry syllabus of Nepal contains the following:

• Physical Chemistry
• Inorganic Chemistry
• Organic Chemistry
• Applied Chemistry

I am going to provide you important questions from each section, making it easier for you to tackle all topics and understand concepts section by section. You can also download the pdf of these most importnat questions of class 12th chemistry using the download button provided in the end of this article.

first, 

Who the hell I am to share this questions with you? and How did I know these are important?

So, I am Shriram Lamichhane, founder of this "The SR Zone" platform. I gave class 12 Board Exams in 2079. Of course, the syllabus and questions were new, syllabus was new, question model was changed. I was so overwhelmed. But, still I made a list of important questions, and started studying them. 

Guess what? I got A+ in chemistry. So, these questions are not made for the sake of "making". These are actually important questions which are most frequently repeated in past year as well. 

Also Read : Class 12 Physics Most Important Questions

Physical Chemistry Important Questions

Some Questions: 

• Define the terms: Normality and Normality factor, End point and Equivalent point, Titration error, Seminormal solution and Decinormal solution, Indicator, Standard solution(primary and secondary) with example.
• What are primary standard substances? What are the requisites for a substance to be the primary standard?
• Define molarity and normality. Write their relationship.
• Predict whether the aqueous solution of CuSO4/CaCl2/Na2CO3/NaCl is acidic basic or neutral. Give a reason.
• State Ostwald’s dilution law.
• Define pH and pOH . Write about their relationship.
• Difference between Absolute Alcohol and Denaturated Alcohol.
• Define the terms:
• Electro chemical equivalent (ECE).
• Standard electrode potential.
• Mention one important application of standard hydrogen electrodes giving an example.
• State first law of thermodynamics and point out its limitation.
• Distinguish between intensive and extensive property with one example of each.
• Define enthalpy of combustion and enthalpy of formation.
• Draw energy profile diagram for exothermic and endothermic reactions.
• Draw energy profile diagram for catalysed and uncatalyzed reactions.( How does catalyst increase the rate of reaction?)
• State second law of thermodynamics. Explain this law on the basis of entropy change.
• Find the unit of rate constant of: zero, first, second and third order reaction.
• Why do transition metals form coloured compounds?
• Why do transition metals act as catalysts?
• Write Short Notes on: Complex Ions, Ligands, Coordination Sphere, d-Block Elements

Topics not to leave at any cost:

• Selection of indicators.
• Different concepts of acids and bases and their limitations
• Common ion effect and solubility product principle and its application.
• Hess law.
• Prediction of feasibility/ spontaneity of reactions in terms of free energy change and entropy change.
• Differences between order and molecularity of reaction.
•  How is single electrode potential generated?
• Electrochemical series and their application
• Factors affecting rate of reaction.
• Numericals are also important from all chapters of physical chemistry!

INORGANIC CHEMISTRY IMPORTANT QUESTIONS

Extraction of:

• (Blister) copper from copper pyrites.
• Steel (Mainly Open Hearth process)
• Iron from iron pyrites.
• Zinc from zinc blende ( sulphide ore).
• Mercury from cinnabar (HgS) ore.

Chemistry of:

• Blue vitriol ( CuSO4.5H2O)
• White vitriol ( ZnSO4. 7H2O)
• Zinc white ( ZnO)
• Calomel (Hg2Cl2)
• Corrosive sublimate (HgCl2)

Some Important short questions of Inorganic Chemistry :

• Copper metal becomes black/green when exposed to air for a long time, why?
• What is Rinman’s green? How is it prepared? Write its one important use.
• Write a molecular formula of Philosopher’s wool. How is it prepared?
• What is Nessler’s reagent? How is it prepared? Give its one use.
• What is the composition of stainless steel? Write its one use.
• Distinguish between quenching and tempering of steel.
• What happens when copper is treated with conc. HNO3?
• What is the effect of heat on blue vitriol?
• Rusting (corrosion) of iron and methods of prevention.
• Why does silver nitrate produce permanent black stains on the skin?

ORGANIC CHEMISTRY IMPORTANT QUESTIONS

• Why is chloroform stored in a dark bottle containing ethanol?
• Why does chloroform not give white ppt. with aq. AgNO3?
• Why is nucleophilic substitution reaction difficult in haloarene?
• Why is the boiling point of ethanol greater than that of ethoxy ethane?
• Why is phenol more acidic than aliphatic alcohol?
• Write a chemical test to distinguish ethanoic acid(acetic acid) from methanoic acid(formic acid).
• Why is chloroacetic acid stronger than acetic acid?
• Why is formic acid stronger than acetic acid?
• Why are amino groups of aniline protected before nitration?(Aniline can not be nitrated directly, why?)
• Write the functional isomers of C3H6O with their IUPAC name. Give a chemical test to distinguish them.
• Write an unsymmetrical ether of C3H8O. How would you prepare this ether using Williamson’s synthesis?
• Write down possible isomeric amines of C3H9N and give their IUPAC names.
• Write monomers and one use of:
• (a)Bakelite    (b)Nylon-6,6      (c)polyvinyl chloride(PVC)     (d) Teflon
• Why does nitrobenzene undergo electrophilic substitution reaction at meta position? 
• Explain why –NO2 group is meta directing towards electrophilic aromatic substitution.
• Why is chlorobenzene o/p – directing towards electrophilic substitution reaction?
• It is dangerous to boil a sample of ether stored for a long time, give reason.
• Ether is stored in a bottle containing iron wire, why?
• Give a suitable test to distinguish ethan-amine from N-methyl methanamine.

Name reactions:

• Aldol condensation reaction
• Cannizaro’s reaction
• Perkins condensation
• Claisen Condensation reaction.
• Benzoin condensation
• Carbylamine reaction
• Reimer Tiemann reaction
• Carbonylation reaction (Oxo process)
• Williamsan’s etherification reaction
• Rosenmund reduction
• Coupling reaction( preparation of azo dyes)
• Diazotization reaction
• Friedel- Craft’s reaction
• Hoffmann’s Bromamide reaction( Decarbonylation reaction)
• Esterification reaction

Test reaction:

• Iodoform test
• Silver mirror test( reaction with Tollen’s reagent)
• Nitrous acid test of 10, 20 and 30 amines.
• 2,4 – DNP test
• Carbylamine test ( test of primary amines)
• Fehling's test
• Important reactions:
• All reactions of chloroform.
• Reduction of nitrobenzene in different mediums.
• Preparation of alcohols using Grignard reagent.
• Oxidation of alcohols.
• Fermentation

Reactions of preparation along with uses:

• DDT 
• Picric acid
• BHC 
• Urotropin
• Chloropicrin
• TNT

Conversion Reactions:

• 1-bromopropane to 2- bromopropane and vice- versa.
• Methanamine to ethanamine and vice versa.
• Phenol to anisole(methoxy benzene) and vice versa.
• Ethoxy ethane to methoxy ethane.
• 1- propanol to 2- propanol and vice versa.
• Ethanol to 2- hydroxy propanoic acid.
• Propanone(acetone) to 2-hydroxy-2-methyl propanoic acid.
• Phenol to toluene.
• Phenol/aniline to azo-dye.
• Ethanal/ ethanol to 3-hydroxy butanal.
• Ethanol to propanol/ propanoic acid.
• Methanamide to ethanamine.

Important Topics from Organic Chemistry

• Lab preparation of Chloroform (Reaction and Principle only)
• Identification of 10, 20 and 30 alcohols by Victor Meyer’s method.
• Separation of 10, 20 and 30 amines by Hoffmann’s method.

What happens when:

• Phenol is treated with benzene diazonium chloride.
• Ethoxy ethane is treated with excess HI.
• Methanal(formaldehyde) is treated with ammonia.
• Methanal / benzaldehyde is treated with NaOH .
• Ethanal/propanone is treated with NaOH .
• Aldehyde/ketone is treated with hydroxylamine.
• Ethanol is heated with conc. H2SO4.
• Acetic acid is treated with P2O5. 
• Aniline is treated with aq. Br2.
• Sodium benzoate is heated with soda lime.
• Phenol is heated with zinc dust.
• Chlorobenzene is treated with chloral .
• Ethyl alcohol(ethanol) is treated with acetic acid(ethanoic acid)
• Phenol is treated with aq. Br2.

Applied Chemistry Important Questions

• Write example and one use of:
• Analgesic , antipyretic, antibiotics and antiseptic drug.
• Herbicide and Pesticide
• Germicide and Insecticide
• Production of cement and paper with detailed process
• Radioactivity and its uses