As students begin their preparation in class 11, they must focus on the fundamentals and build a solid foundation of principles. This is especially significant in Chemistry since it necessitates a thorough understanding of a wide range of topics that will be useful in the future. The difficulty level of questions in the 12th board examinations is higher. Aspirants can expect many questions from topics such as balancing equations and mole concepts in the JEE Main 2022 exam.
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Aspirants should take as many mock tests as possible; this JEE Main Chemistry Important Questions and Answers will help students comprehend the various topics and prepare for examinations. It contains all of the crucial JEE Mains Chemistry questions and answers. Students can use these questions for revision and must check them regularly.
Also See: JEE Main Previous year questions
1. What does BOD stand for?
BOD stands for Biochemical Oxygen Demand.
2. The upper stratosphere of the ozone layer protects us from the sun’s radiation that falls in which wavelength region?
The Ozone protects us from the sun’s radiation that falls in the 200-315 nm wavelength region.
3. What substance used in dry cleaning is a better strategy to control environmental pollution?
Liquid carbon dioxide is better for replacing conventional halogenated solvents (potentially carcinogenic).
4. Name the structure of silicate in which two oxygen atoms of [SiO4]4- are shared.
In linear chain silicate, two oxygen atoms per tetrahedron are shared.
5. Monosaccharides and disaccharides are differentiated by?
Carbohydrates are polyhydroxy aldehydes and ketones. Carbohydrates may have an aldehyde group (aldoses) or ketose group. Barfoed’s test distinguishes monosaccharides from disaccharides. In this test, copper acetate in dilute acid is reduced in 30 seconds by monosaccharides, whereas disaccharides take several minutes.
6. Which alkene exhibits geometrical isomerism?
The compounds which are of the same molecular formula but differ in the relative spatial arrangement of atoms or groups in space are geometrical isomers. This phenomenon is called geometrical isomerism. 2-butene exists as trans or cis. It exhibits geometric isomerism because of the restricted rotation around the double bond.
7. What is the similarity between optical and geometrical isomerism?
Optical isomerism and geometrical isomerism are included in stereoisomerism.
8. A racemic mixture is formed by mixing which two components?
A racemic mixture is formed when d and l forms of optical isomers are mixed in equimolar proportion.
9. Which alkene exhibits geometrical isomerism?
2- butene exhibits geometrical isomerism.
10. Which combinations would act as a propellant for rockets?
Oxygen is a strong supporter of combustion. Liquid hydrogen has a low mass and high enthalpy of combustion. Liquid hydrogen and liquid oxygen are used as excellent fuels for rockets.
11. What is the distillation technique most suited for separating glycerol from spent-lye in the soap industry?
The distillation technique most suited for separating glycerol from spent-lye in the soap industry is distillation under reduced pressure. The boiling point of glycerol is 2900C at atmospheric pressure. At this temperature, it decomposes before it distils. Therefore, the distillation is carried out under reduced pressure by applying a vacuum which decreases the boiling temperature of glycerol and thus prevents its decomposition.
12. Which types of drugs reduce a fever?
Antipyretics are used to reduce the temperature.
13. What is aspirin known as?
Aspirin is known as Acetylsalicylic acid.
14. Regular use of which fertilisers increases the acidity of soil?
Ammonium sulphate is a salt of strong acid and weak base. It produces H+ ions on hydrolysis. This helps to increase the acidity of the soil.
15. What is DDT?
DDT is a non-biodegradable pollutant.
16. A red solid is insoluble in water. However, it becomes soluble if KI is added to the water. Heating the red solid in a test tube results in the liberation of some violet-coloured fumes, and droplets of metal appear on the test tube’s cooler parts. What is the red solid?
On heating, HgI2 decomposes as HgI → Hg + I2.
17. Which nuclear reactions will generate an isotope?
Neutron particle emission will generate an isotope.
18. Polymer formation from monomers starts by?
Polymerisation begins with monomer addition or condensation processes.
17. Bakelite is obtained from phenol by reacting with which chemical?
Bakelite is obtained from phenol by reacting with formaldehyde HCHO.
18. Which chemical is classified as a condensation polymer?
Dacron is a condensation polymer. Teflon, neoprene, and acrylonitrile are additional polymers.
19. What type of polymer is used to produce paints and lacquers?
Glyptal is a substance used in the production of paints and lacquers.
20. Which species can best serve as an initiator for cationic polymerization?
AlCl3 can serve as an initiator for cationic polymerization.
21. What are Nylon threads made of?
Nylon is a polyamide. It is made from reacting carbon-based chemicals found in coal and petroleum in a high-pressure, heated environment.
22. Formation of Bakelite is followed by?
The formation of Bakelite follows electrophilic substitution followed by condensation.
23. What are the two monomers for the synthesis of Nylon 6,6?
Monomers of Nylon 6,6 are adipic acid and hexamethylenediamine.
24. What is the Copper wire test for halogens known as?
The copper wire test for halogens is known as Beilstein’s Test.
25. Which of the following elements is estimated using the Beilstein test?
The Beilstein test is a chemical test used to identify organic halides. Cl belongs to the halogen group.
26. Which of the salts is the most basic in an aqueous solution?
CH3COOK + H2O → CH3COOH + KOH. KOH is a strong base, and CH3COOH is a weak acid. So the solution is essential.
27. Fire extinguishers contain H2SO4, and which one other element?
Fire extinguishers contain H2SO4 and NaHCO3.
28. When heated with concentrated sulphuric acid and a soluble chloride, potassium dichromate gives brown-red vapours of which element?
When potassium dichromate is heated with concentrated H2SO4 and a soluble chloride, brownish-red vapours of chromyl chloride are formed.
29. How many electrons are involved in the below redox reaction?
Cr2O72- + Fe2+ + C2O42- → Cr3+ + Fe3+ + CO2 (unbalanced)
Cr2O72- + 2Fe2+ + 2C2O42- → 2Cr3+ + 2Fe3+ + 4CO2
6 electrons are involved in this reaction.
30. Copper turns into green when exposed to moist air for an extended period. What is the reason behind it?
The copper metal turns green in colour when exposed to air because of corrosion. The metal reacts with moisture and atmospheric gases to form a copper carbonate and copper hydroxide mixture.
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31. Which alcohols would react fastest with conc. HCl and anhydrous ZnCl2?
2-Methylpropan-2-ol is a tertiary alcohol. It reacts fast with conc. HCl and anhydrous ZnCl2.
32. Ether is more volatile than alcohol, having the same molecular formula. This is because?
Ether is more volatile than alcohol, having the same molecular formula. This is due to intermolecular hydrogen bonding in alcohols.
33. A liquid was mixed with ethanol, and a drop of concentrated H2SO4 was added. A compound with a fruity smell was formed. What is the liquid?
The fruity smell is the characteristic property of ester. So the reaction leads to the formation of ester. It is called esterification.
34. Unknown alcohol is treated with the “Lucas reagent” to determine whether the alcohol is primary, secondary, or tertiary. Which alcohol will react fastest, and by what mechanism?
Lucas’s test is done to differentiate between primary, secondary, and tertiary alcohols. This is based on the difference in reactivity of the three classes of alcohols with hydrogen halides. The reaction proceeds through carbocation formation as tertiary carbocation is highly stable. Then the reaction proceeds through SN1 with tertiary alcohol.
35. What is the best reagent to convert pent-3- en-2-ol into pent-3-en-2-one?
Chromic anhydride in glacial acetic acid is used to convert a secondary alcohol to a ketone.
36. Does Acetyl bromide react with an excess of CH3MgI followed by treatment with a saturated solution of NH4Cl?
The reaction will give tertiary alcohol.
37. Which chemicals can exhibit the most significant number of oxidation states?
Manganese can show six oxidation states from +2 to +7. It has five unpaired electrons in 3d orbitals and 2 electrons in the 4s orbitals.
38. Which isomerism is present in nitro- pentaammine chromium (III) chloride?
The nitro group can attach to metal through nitrogen (-N02) or oxygen as nitrate (-ONO). So isomerism in nitro-pentaammine chromium (III) chloride is linkage isomerism.
39. The actinoids exhibit more oxidation states in general than the lanthanides. Why?
Since the distance between the nucleus and 5f orbitals is more than the distance between the nucleus and 4f orbitals, the hold of the nucleus on valence electrons decreases in actinides. So actinoids exhibit more oxidation states in general.
40. In the Goldschmidt aluminothermic process, which reducing agent is used?
In Goldschmidt, the aluminothermic process aluminium is used as the reducing agent.
41. Which metal cannot be obtained by electrolysis of an aqueous solution of its salts?
Calcium is a metal that cannot be obtained by the electrolysis of an aqueous solution of its salts. It can be obtained by the process of electrolysis of molten CaCl2.
42. Which metal is extracted by leaching with cyanide?
Silver is extracted by leaching with cyanide.
43. Which element essentially causes Smog?
Smog is smoke + fog. It is caused by a mixture of smoke and sulphur dioxide.
44. Which oxide groups cannot be reduced by carbon?
Highly reactive metals like K and Ca can not be reduced by carbon. The oxides of less electropositive metals like Fe, Zn, Pb, Cu, Sn, etc., are reduced by strongly heating them with coke or coal in the blast furnace.
45. Which ores are best concentrated by the froth-flotation method?
The froth-floatation method is used for the concentration of sulphide ores. Here galena (PbS) is the only sulphide ore.
46. Haemoglobin and gold sol are examples of?
Haemoglobin and gold sol are examples of positively and negatively charged sols, respectively.
If you are studying for the JEE Main, you should be aware that the Chemistry topic is quite crucial because it is one of the sections where students can obtain the most marks. While candidates must be familiar with ideas and formulae, they must also be familiar with questions, paper patterns, marking schemes, and other factors. These JEE Main Chemistry questions and answers will guide every student in effectively preparing for and achieving the highest possible rank in the JEE Main examination.