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Chemistry Short questions from class 12. Every student should learn to attempt before go to exams.

Class12 Chemistry Short questions (Guess)

Class12 Chemistry Long questions (Guess)

Class12 Chemistry (full book solved short questions and long questions)

If you are interested for solved short question from chapter 3,4,5,14,15,16. All important board questions are available.

And if you are looking for long questions and notes like stuff, they are available.

 Chapter 1

1. Define atomic radius. How it varies in groups?
2. Why size of cation is smaller while size of anion is greater than parent atom?
3. Why ionization energy decreases down the group and increases across a period?
4. Why 2nd ionization energy is greater than 1st one?
5. Why 2nd electron affinity is shown with positive sign?
6. Why oxides of metals are basic while non-metals are acidic?
7. How melting points change across short periods?
8. Why oxidation state of noble gases is zero?
9. The oxidation states vary in a period, but remain constant in a group. Explain.
10. Why diamond is non-conductor while graphite is conductor of electricity?
11. Although both sodium and phosphorus are present in the same period of periodic table, yet their oxides are different in nature, Na₂O is basic while P₂O₅ is acidic. Explain.
12. What is lanthanide contraction?
13. On what factors electrical conductivity depends? How it varies in periodic table?
14. What are the improvements made by Moseley in Mendeleev’s periodic table?
15. Define modern periodic law.

Chapter 2

1. What are alkali and alkaline earth metals? Give one example in each case.
2. Why alkali and alkaline earth metals are the most reactive elements in periodic table?
3. Write down formulae of natron, halite, white, beryl, asbestos, and Chile saltpeter.
4. What is effect of heat on NaNO₃ and LiNO₃?
5. Justify that BeO is amphoteric oxide.
6. What is the effect of heat on hydroxide of group IA?
7. Write down three advantages of Down’s cell.
8. Which two major problems are faced during working of diaphragm cell?
9. What is plaster of paris? How is it prepared?
10. Why limewater turns milky on passing CO₂? What happens when an excess of CO₂ is passed through limewater?
11. What is milk of magnesia? Write down its use.
12. Why aqueous solution of Na₂CO₃ is basic?
13. What is the function of calcium in plant growth?
14. What is the role of gypsum in the metal industry?
15. Why potassium superoxide is used in breathing types of equipment for mountaineers and in space crafts?
16. Why 2% gypsum is added to the cement?
17. Why lime is added to acidic soils?

Chapter 3

1. How aluminium metal is used to remove air bubbles from molten metals?
2. What is borax? Write down its preparation from colemanite and boric acid.
3. How boric acid is prepared on a commercial scale?
4. What is a chemical garden?
5. Describe chemistry of borax bead test.
6. Give four uses of borax.
7. How does borax serve as a water softening agent?
8. What are the different types of boric acids?
9. What is the effect of heat on orthoboric acid (boric acid)?
10. Give uses of boric acid. How does boric acid react with NaOH and C₃H₅OH?
11. How weathering phenomenon converts potassium feldspar into clay?
12. Why is CO₂ acidic in nature? Why CO₂ is gas while SiO₂ is solid in nature?
13. What are the uses of sodium silicate?
14. Why are liquid silicones preferred over ordinary organic lubricants?
15. How aluminium reacts with caustic soda, hydrogen gas, halogens and sulphuric acid?
16. Why aluminium is not found as in a free element?
17. Write down the uses of aluminium.

Chapter 4

1. How nitrogen dioxide is prepared from (a) lead nitrate (b) Cu + HNO₃
2. Justify that NO acts as an oxidizing agent.
3. What is ring test?
4. Show with two examples that NO₂ is an oxidizing agent.
5. Justify that sulphuric acid is a dehydrating agent by writing two equations.
6. Write down reactions of HNO₃ with Zn.
7. Nitric acid is a strong oxidizing agent. Give three examples to support the statement.
8. What is the effect of heat on phosphoric acid?
9. What is aqua regia? How it dissolves gold?
10. Write down the reaction of P₂O₅ with cold and hot water.
11. Differentiate between oxygen and sulphur.
12. Why is SO₃ dissolved in H₂SO₄ but not in the water?
13. P₂O₅ is a powerful dehydrating agent. Prove giving examples.
14. H₂SO₄ is strong oxidizing agent. Give three examples to support the statement.
15. Give four uses of nitric acid. Describe similarities between oxygen and Sulphur.
16. Give advantages of contact process.

Chapter 5

1. How fluorine is different from other members of the family?
2. What is a disproportionation reaction? (Write down the reaction of chlorine with cold and hot NaOH.)
3. Why fluorine is a strong oxidizing agent than chlorine?
4. On what factors oxidizing power of halogens depends?
5. How are halogen acids ionized in water?
6. Why HF is weaker acid than HI?
7. How is the activity of bleaching powder measured? (What is available chlorine?)
8. What happens when bleaching powder reacts with CO₂, HCl, NH₃ and dilute sulphuric acid?
9. What is iodized salt? Where is it used?
10. Why iodine has a metallic luster?
11. Write down the uses of those gases.
12. What is the structural formula of Teflon?
13. Mention its two uses. Describe Hasenclever’s method for the formation of bleaching powder.
14. What are freons?
15. What is halothane? Mention its one use.
16. Give four uses of halogens.
17. Write uses of bleaching powder.

Chapter 6

1. Differentiate between typical and non-typical transition elements.
2. What is paramagnetism?
3. Define individual compounds.
4. Why some of the salts of transition metals are coloured?
5. Define central metal ion and ligand.
6. Define coordination number and coordination sphere.
7. What are chelates?
8. What are substitutional alloys?
9. What are commercial forms of iron?
10. KMnO₄ is a strong oxidizing agent. Justify giving examples.
11. What is the chromyl chloride test?
12. Why does damaged tin-plated iron get rusted quickly?
13. Write down methods used for the prevention of corrosion.
14. How does the process of galvanizing protect the iron from rusting?
15. What is sacrificial corrosion?
16. How are untapped bubbles removed from steel?
17. Write systematic names of the following complexes:
    1. [Fe(CO)₅]
    1. [Co(NH₃)₆]Cl₃
    1. [Fe(H₂O)₆]²⁺
    1. Na₃[CoF₆]
    1. K₂[Cu(CN)₄]
    1. K₂[PtCl₆]

Chapter 7

1. Define organic chemistry. What is the vital force theory?
2. What is the importance of Wohler’s work in chemistry?
3. Define carbonization. How is coal produced from the remains of the trees?
4. 4.Define cracking. Write the names of different types of cracking.
5. What is reforming? (How can the quality of gasoline be improved?)
6. Define octane number. How can it be improved?
7. Name four homocyclic compounds which are not aromatic.
8. Define heterocyclic and alicyclic compounds.
9. Define functional group. Write down three functional groups containing oxygen.
10. What is cis-trans isomerism? Why is there free rotation around sigma bond but not around pi-bond?
11. Define tautomerism and chain isomerism.
12. Define metamerism and position isomerism with example.
13. There is no cis-trans isomerism in 1-butene but 2-butene shows.

Chapter 8

1. Describe Clemenson and Wolf-Kishner’s reduction.
2. Write reaction mechanism for the preparation of ethane by Kolbe’s process.
3. Why alkanes are less reactive than alkenes?
4. What is Raney nickel and for what it is used?
5. What is Sabatier-Sendem’s method for the preparation of alkanes?
6. How alkenes are prepared by dehydrohalogenation and dehydration?
7. How will you prepare cis-2-butene from an alkyne? Give a reaction.
8. How will you establish that ethylene contains a double bond?
9. State Markovnikov’s rule.
10. How will you convert ethene into ethyl alcohol and formaldehyde?
11. Write down the industrial preparation of acetylene.
12. Differentiate between ethene and ethyne?
13. How will you convert ethyne into ethanol and oxalic acid?
14. Convert ethyne into ethane and benzene.
15. How does ethyne react with hydrogen and halogen acid?
16. How ethene is converted into ethylene epoxide and polythene?
17. Write two uses of each of ethene and ethyne.

Chapter 9

1. What is meant by the term aromatic? Write down the classification of aromatic hydrocarbons.
2. What are the results of X-ray studies of benzene molecule?
3. Define resonance and resonance energy (Draw resonance structures of benzene.)
4. Write two objections to Kekule’s formula of benzene.
5. How is benzene prepared in the laboratory?
6. Give mechanism of nitration.
7. Convert benzene into m-chloronitrobenzene.
8. Why benzene is less reactive than alkenes?
9. Convert benzene into p-chloronitrobenzene.
10. How benzene is converted into oxalic acid?
11. Write down formula for toluene, aniline, acetophenone and benzophenone.
12. What is Wurtz-Fittig reaction?
13. Prove that benzene has a cyclic structure.
14. What happens when mixture of benzene vapors and air are passed over heated vanadium pentoxide? (Give catalytic oxidation of benzene.)
15. Give four meta-directing and four ortho-para directing groups.
16. What happens when acidified KMnO₄ is treated with ethylbenzene and methylbenzene?
17. How benzene is prepared on large scale?

Chapter 10

1. Define alkyl halides. Write down their classification.
2. What is the best method for the preparation of alkyl halides?
3. Describe Wurtz’s reaction. (How are alkyl halides reduced to alkanes?)
4. Define electrophile and nucleophile.
5. What are leaving group and substrate?
6. Convert ethyl bromide into butane, ethylene and propanoic acid.
7. What is Grignard reagent? Write down a reaction to prepare ethyl magnesium bromide in the laboratory.
8. How ethyl magnesium bromide reacts with ammonia, water and ethanol?
9. How Grignard reagent is used to get primary, secondary and tertiary alcohols?
10. What is the reason for the reactivity of Grignard reagent?
11. Discuss the reactivity of alkyl halide based on bond energy.
12. Write down mechanism of Sₙ1 reaction (Justify that Sₙ1 is a unimolecular reaction). Describe mechanism of E2 reaction.
13. Write down mechanism of Sₙ2 reaction. (Justify that Sₙ2 is a bimolecular reaction.)
14. What are β-elimination reactions?
15. How tetraethyl lead is prepared from alkyl halide?
16. Give a method for the preparation of alkyl iodide.

Chapter 11

1. Write down the formula of lactic acid, tartaric acid and ethylene glycol.
2. How is wood spirit prepared from water gas?
3. How ethanol is obtained from molasses and starch?
4. Why alcohol obtained in the fermentation process never exceeds 14%? (Absolute Alcohol cannot be prepared by the Fermentation process, why?)
5. Define fermentation and oxonium ion.
6. How ethyl alcohol is denatured?
7. Define absolute alcohol and rectified spirit.
8. How will you chemically differentiate between methanol and ethanol?
9. Ethyl alcohol is a liquid but ethyl chloride is gas. Why?
10. What is Lucas test for the distinction of primary, secondary and tertiary alcohols?
11. Ethanol gives different products with sulfuric acid under different conditions. Give reactions.
12. Why phenol shows more acidic behavior than alcohols but benzene cannot show acidic behaviour?
13. Write down the uses of methanol and ethanol.
14. Convert phenol into Bakelite and picric acid.
15. How will you prepare diethyl ether by Williamson synthesis?
16. Write two methods for the preparation of phenol.
17. Write down the reaction of diethyl ether with HI and PCl₅.

Chapter 12

1. Write down the industrial and laboratory preparation of methanol.
2. Write down the industrial and laboratory preparation of ethanol.
3. How formaldehyde reacts with concentrated NaOH and NaHSO₃?
4. 4.Write down the mechanism of addition of HCN to carbonyl compounds.
5. What is Cannizzaro reaction? What types of aldehydes give this reaction?
6. Distinguish between ethanol and propanal.
7. Prepare metaformaldehyde and paraldehyde.
8. Write down the uses of formaldehyde and acetaldehyde.
9. Differentiate between acetone and acetaldehyde. (Differentiate between ketones and aldehydes.)
10. What is Tollen’s reagent? Where is it used?
11. What is Fehling solution and Benedict’s solution test?
12. How lactic acid and ethanoic acid are prepared from ethanol?
13. What type of compounds gives iodoform reaction?
14. Write down the general mechanism of base-catalyzed addition
15. reactions.
16. Write reaction of hydroxylamine with ethanol and propanone.
17. Distinguish between acetaldehyde and paraldehyde.

Chapter 13

1. Convert 2-butene and methyl cyanide into acetic acid.
2. How acetic acid is converted into acetamide and acetyl chloride?
3. What is Zwitter ion? What are neutral amino acids?
4. What are acidic, basic and neutral amino acids?
5. What are fatty acids? Give two examples.
6. Write down Strecker method for amino acid preparation.
7. What is a peptide bond? Write down the formula of dipeptide.
8. Differentiate between polypeptide and protein.
9. Write uses of acetic acid.
10. Write the mechanism of reaction between acetic acid and ammonia.
11. What are essential and non-essential amino acids?
12. Why carboxylic acids have high boiling points than alcohols? (Draw a dimer of carboxylic acid.)
13. How acetic acid is converted into methane and acetic anhydride?
14. How acetic acid reacts with (a) PCl₃ (b) SOCl₂
15. Convert acetic acid into ethanol and ethane.
16. What are aliphatic and aromatic carboxylic acids?
17. What is vinegar? How is it prepared from ethanol?

Chapter 14

1. What are macromolecules (polymers)? Give their classification.
2. What is glycogen? Give its properties.
3. What are the different types of polymers based on the effect?
4. What is an addition polymerization? Give an example. (How polyvinyl chloride is prepared?)
5. What are condensation polymers? (How nylon-6,6 is prepared?)
6. Differentiate between α-D-glucose and β-D-glucose by making structure.
7. Differentiate between amylose and amylopectin.
8. What are proteins? Write down their classification. (Name different types of proteins based on physicochemical properties.) Describe the importance of proteins and lipids.
9. In what respects fats and oils are different?
10. What is saponification?
11. What is rancidity of fats? Why it occurs?
12. Define purification number, acid number and iodine number. What is the hardening of oils? Draw structure of cholesterol.
13. Differentiate between DNA and RNA.
14. Discuss epoxy resins. What are their uses?
15. Define homopolymer and copolymer with example.
16. How proteins are denatured?

chapter 15

1. What are fertilizers?
2. What are the essential chemical nutrient elements?
3. What are the qualities of good fertilizer?
4. What is the importance of nitrogen and phosphorous fertilizers?
5. Write formulae and names of two phosphate fertilizers.
6. What is the role of potassium in proper plant growth?
7. Define cement. Write down raw materials.
8. What is the composition of Portland cement?
9. What is meant by the setting of cement? Write down reactions taking place in 24 hours.
10. Briefly describe the bleaching process of pulp.
11. Write about the digestion process for the preparation of pulp.
12. Define paper. Write down raw materials for paper manufacturing.
13. What are the different pulping processes?
14. Why NH₄NO₃ is not useful in paddy rice fields?
15. What is a clinker? Why 2% gypsum is added to the cement?
16. Name different parts of paper making machine.

Chapter 16

1. Define environmental chemistry. Write the names of components of the environment.
2. What are the disadvantages of acid rain?
3. What is smog? What are the main conditions for the formation of photochemical smog?
4. Define environmental pollutant. What are primary and secondary pollutants?
5. Write a note on the lithosphere. What is biosphere?
6. How chlorofluorocarbons destroy ozone? (Why is the ozone layer depleting?)
7. What are detergents? How they affect the purity of water?
8. What is dissolved oxygen? How will you check the purity of water?
9. What are COD and BOD?
10. What is leachate?
11. What are the main sources of SO₂ as air pollutants?
12. Oil spillage affects marine life. Justify.
13. Ozone is a blessing in stratosphere while a curse in troposphere. Justify.