Maharashtra HSC Chemistry Exam 2026 LIVE: Exam Tomorrow; Important Questions, Weightage & Expert Tips

Maharashtra HSC Chemistry Exam 2026:The Maharashtra HSC Chemistry exam is scheduled for February 18, 2026, from 11 AM to 2 PM. This is the part of the Class 12 board tests taking place from February 10 to March 11 this year. If you are appearing for Chemistry, keep reading! In this live blog, we are providing the most important questions you should focus on, how marks are distributed across chapters, and simple revision tips from experts to help you improve your score. Stay tuned for Maharashtra HSC Chemistry exam updates, focus on smart preparation, and get ready to write your best paper yet. We will be providing the Chemistry answer key along with student reviews through the same live blog on Wednesday, February 18.

Maharashtra HSC Chemistry Exam 2026: Quick Facts

Check below some of the facts and important details related to the Maharashtra HSC Chemistry Exam 2026:

Also Read:Maharashtra HSC Physics Answer Key 2026

So, as the Maharashtra HSC Chemistry exam on February 18, 2026, is getting closer and closer, remember that this is your chance to give your best. Instead of stressing about how tough the paper might be, think about how you can use the three hours wisely. Attempt the questions you are most confident about first. Keep your answers neat and to the point. This exam is important, yes, but it is also manageable. You’ve got this! Any latest update pertaining to the HSC Chemistry exam shall be provided through the live blog below.

Also read |JEE Main Toppers List 2026 LIVE Updates

Maharashtra HSC Chemistry Exam 2026 LIVE Updates

• Feb 17, 2026 09:00 PM IST

  Maharashtra HSC Chemistry Repeated Numerical Concepts

  • First-order half-life formula t½ = 0.693 / k
  • Nernst Equation
  • Raoult’s Law
  • pH of buffer solution
  • Solubility product (Ksp)
  • Faraday’s Laws of Electrolysis

• Feb 17, 2026 08:30 PM IST

  What is nano material?

  Nanomaterials are materials having at least one of their dimensions in the size range of 1 to 100 nanometres (nm).

  Due to their extremely small size, nanomaterials show unique physical, chemical, electrical and optical properties which are different from their bulk materials. These special properties arise because of their large surface area to volume ratio.

  Examples: Nanoparticles of gold, silver, carbon nanotubes, etc.

  
   

• Feb 17, 2026 08:00 PM IST

  Wolff-Kishner reduction reaction

  Wolff-Kishner reduction is a chemical reaction used to convert aldehydes and ketones into corresponding alkanes by reducing the carbonyl group (>C=O) to a methylene group (-CH₂-).

  In this reaction, the carbonyl compound is heated with hydrazine (NH₂NH₂) in the presence of a strong base such as KOH in ethylene glycol.

  The reaction occurs in two steps:

  1. Formation of hydrazone.
      
  2. Decomposition of hydrazone on heating to give alkane with evolution of nitrogen gas.

  Thus, the Wolff-Kishner reduction is used for the complete reduction of aldehydes and ketones to alkanes.

• Feb 17, 2026 07:30 PM IST

  Chemical Kinetics Question with Solution

  Q: 60% of the reactant decomposes in 45 minutes in a first order reaction. Calculate the half life period of the reaction.

  Given:
  60% of the reactant decomposes in 45 minutes. Therefore, 40% of the reactant remains.

  Initial concentration = a
  Amount remaining after 45 min = 0.4a

  Hence, the half-life of the reaction is 34.14 minutes.

• Feb 17, 2026 06:30 PM IST

  Some Important 4-Mark Questions from Chemical Thermodynamics

  Q: (a) Define the following terms:
      (i) Enthalpy of atomization
      (ii) Extensive properties

  (b) Write the mathematical statement of the first law of thermodynamics for the following processes:
      (i) Isothermal process
      (ii) Adiabatic process

  Q: (a) Define the following terms:
      (i) Bond enthalpy
      (ii) Enthalpy of ionization

  (b) Calculate the standard enthalpy of the reaction:

  Q: (a) Classify the following into intensive and extensive properties. Pressure, volume, mass, temperature. 

  (b) Define a state function and write two examples of it.

• Feb 17, 2026 06:00 PM IST

  Some Important 3-Mark Questions from Chemical Thermodynamics

  Q: (a) Define an isolated system.
  (b) Three moles of an ideal gas are expanded isothermally from 15 dm³ to 20 dm³ against a constant external pressure of 1.2 bar. Calculate the amount of work done in joules.
   

  Q: (a) Define enthalpy of fusion.
  (b) Derive an expression for the maximum work done by a system.

  Q: (a) Derive the expression: ΔH = ΔU + PΔV.
  (b) Write the relationship between heat (Q) and change in internal energy (ΔU) for an isochoric process.

  Q: (a) Define standard enthalpy of formation.
  (b) Derive the relationship between the standard enthalpy of reaction and the standard enthalpies of formation of reactants and products for the reaction:

  aA + bB → cC + dD.

  
   

• Feb 17, 2026 05:30 PM IST

  Some Important 2-Mark Questions from Chemical Thermodynamics

  • Define the terms: (i) Standard enthalpy of combustion (ii) Enthalpy of sublimation. 
  • State and explain Hess's law of constant heat summation. 
  • Write the features of reversible processes.
  
   

• Feb 17, 2026 05:00 PM IST

  Some Important 1-Mark Questions from Chemical Thermodynamics

  • An intensive property amongst the following is………….
  • The work done in the dm3bar when 200 mL of ethylene gas and 150 mL of HCl gas were allowed to react at 1 bar pressure is….
  • Write the expression to calculate the maximum work done when 1 mole of an ideal gas expands isothermally and reversibly from V1 to V2. 
  • Write the mathematical relation between ∆H and ∆U during the formation of one mole of CO2 under standard conditions.
  
   

• Feb 17, 2026 04:30 PM IST

  Important Order-Based Question from Chemical Bonding and Molecular Structure

  Arrange the following in increasing order of the property mentioned: 

  (i) HOCl, HClO2, HClO3, HClO4 (acidic strength)

  (ii) MF, MCl, MBr, MI (ionic character) 

  (iii) HF, HCl, HBr, HI (thermal stability)

  
   

• Feb 17, 2026 04:00 PM IST

  Some more important 4-mark questions for HSC Chemistry

  Q: Convert the following:
  (i) Acetaldehyde to isopropyl alcohol.
  (ii) Cumene to phenol.
  (iii) Anisole to phenol.
   Write two uses of neon.

  Q: Define:
  (i) Extensive and intensive properties.
  (ii) Isobaric and adiabatic processes.
  What are enzymes?
  Write the atomic numbers of transuranium elements.

  Q: A solid element has a cubic lattice with edge length 400 pm and density 6.25 g mL⁻¹. The atomic mass of the element is 60. Predict the type of cubic lattice.

  Define nanoscience.
  Write the chemical reaction for the preparation of polyacrylonitrile.

  Q: Derive the relation between the half-life period and the rate constant for a first-order reaction.
  Write the net cell reaction during the discharging of a lead accumulator.
  Draw the structure of peroxymonosulphuric acid.

  Q: Mention the number of unpaired electrons and geometry of the following complexes:
  (i) [NiCl₄]²⁻
  (ii) [Ni(CN)₄]²⁻

  Convert the following:
  (a) Ethanenitrile into ethanal.
  (b) Cyclohexane into adipic acid.

• Feb 17, 2026 03:30 PM IST

  What is osmotic pressure?

  Osmotic pressure is the minimum pressure that must be applied to a solution to stop the flow of solvent molecules into it through a semipermeable membrane. It is a colligative property and depends only on the number of solute particles present in the solution.

  Mathematically, osmotic pressure is given by the equation: π=CRT

  Where,
  π = osmotic pressure
  C = molar concentration of solution
  R = gas constant
  T = temperature in Kelvin

  It is usually expressed in atmospheres (atm).

  
   

• Feb 17, 2026 03:00 PM IST

  Ionic Equilibrium: All Important Formulas to Remember

• Feb 17, 2026 02:30 PM IST

  Some Important 4-Mark Questions from Ionic Equilibrium

  Q: (a) Derive the equation

  (b) Distinguish between strong electrolyte and weak electrolyte

  Q: (a) Explain the amphoteric nature of water. 

  (b) Define i) Solubility product ii) Hydrolysis of salt

  
   

• Feb 17, 2026 02:00 PM IST

  Some Important 3-Mark Questions from Ionic Equilibrium

  • Define buffer solution. Explain its types. 
  • Write one application for each of the following buffers.
  • Derive the equation that implies that the degree of dissociation of a weak acid is inversely proportional to the square root of its concentration.
  
   

• Feb 17, 2026 01:30 PM IST

  Some Important 2-Mark Questions from Ionic Equilibrium

  • Define the following terms i) pH ii) pOH 5) Define molar solubility. Write its unit.
  • Explain Ostwald’s dilution law for weak acids. 
  • Explain Ostwald’s dilution law for weak bases. 
  • Write any four applications of buffer solution
  
   

• Feb 17, 2026 01:00 PM IST

  Some Important 1-Mark Questions from Ionic Equilibrium

  • What is the percentage dissociation of 0.1 M Solution of acetic acid?
  • In the biochemical system, the pH of blood in our body is maintained due to the following buffer
  • If ‘IP’ is the ionic product and ‘ksp’ is the solubility product, precipitation of the compound will occur under the condition when.
  •  Write the name of buffer which is used to maintain pH of 8 to 10 for precipitation of cations of III A group in qualitative analysis 
  • Write the solubility product of sparingly soluble salt Bi2S3 
  • What is the pOH if the hydrogen ion concentration in solution is
  
   

• Feb 17, 2026 12:30 PM IST

  Applied Chemistry Expected Weightage for 2026

  Topic Number	Chapter Name	Weightage Distribution without Options	Weightage Distribution with Options
  Applied Chemistry	Biomolecules	3-4 marks	4-5 marks
  	Introduction to Polymer Chemistry	3-4 marks	4-5 marks
  	Green Chemistry and Nano Chemistry	3-4 marks	4-5 marks

• Feb 17, 2026 12:00 PM IST

  Organic Chemistry Expected Weightage for 2026

  Topic Number	Chapter Name	Weightage Distribution without Options	Weightage Distribution with Options
  Organic Chemistry	Halogen Derivatives	5-6 marks	6-7 marks
  	Alcohols, Phenols, and Ethers	4-5 marks	6-7 marks
  	Aldehydes, Ketones, and Carboxylic Acids	5-6 marks	7-8 marks
  	Amines	3-4 marks	4-5 marks

• Feb 17, 2026 11:30 AM IST

  Inorganic Chemistry Expected Weightage for 2026

  Topic Number	Chapter Name	Weightage Distribution without Options	Weightage Distribution with Options
  Inorganic Chemistry	Elements of Groups 16, 17, & 18	5-6 marks	7-8 marks
  	Transition & Inner Transition Elements	5-6 marks	7-8 marks
  	Coordination Compounds	5-6 marks	7-8 marks

• Feb 17, 2026 11:00 AM IST

  Physical Chemistry Expected Weightage for 2026

  Topic Number	Chapter Name	Weightage Distribution without Options	Weightage Distribution with Options
  Physical Chemistry	Solid State	3-4 marks	5-6 marks
  	Solutions	4-5 marks	5-6 marks
  	Ionic Equilibrium	4-5 marks	5-6 marks
  	Chemical Thermodynamics	5-6 marks	7-8 marks
  	Electrochemistry	5-6 marks	7-8 marks
  	Chemical Kinetics	4-5 marks	5-6 marks

• Feb 17, 2026 10:30 AM IST

  How to Download PYQs for Chemistry?

  Step 1: Go to the official website of the Maharashtra HSC Board at mahahsscboard.in.

  Step 2: Once you are on the homepage, look for the student section. Find the link related to previous year question papers or model question papers and click on it.

  Step 3: Select Class 12 (HSC) from the list of classes, then choose Chemistry as your subject.

  Step 4: Now, select the specific year for which you want to access the question paper.

  Step 5: Check that you have selected the correct class, subject, and year. Then proceed to download the Maharashtra HSC Chemistry previous year question paper in PDF format.

  Step 6: Save the file on your device and start solving it to improve your speed, accuracy, and overall exam readiness.

• Feb 17, 2026 10:00 AM IST

  Maharashtra HSC Chemistry Exam 2026 Last Day Reminder!

  The Chemistry paper will be conducted in the morning session from 11:00 AM to 2:00 PM. Students are advised to reach the exam centre at least 30 minutes before 11:00 AM, preferably by 10:30 AM to avoid last-minute rush.

• Feb 17, 2026 08:37 AM IST

  HSC Chemistry Exam 2026 Tomorrow: Is the question paper leaked?

  Multiple rumours have been circulating onthe  Maharashtra HSC paper leak. There were rumours on HSC Physics paper leak as well. Students must note that there were no instances of paper leak reported officially by the board or Police Department. There is no scope for the leak of Chemistry paper as well. 

• Feb 17, 2026 08:00 AM IST

  Maharashtra HSC Chemistry Exam 2026 Last Day Prep Tips

  • Do not rely on any YouTube video claiming it has the exact question paper.
  • Ignore leaked paper rumors and focus only on your syllabus.
  • Revise important formulas, reactions, and definitions once more.
  • Go through previous years’ Maharashtra HSC Chemistry question papers.
  • Focus more on high-weightage chapters instead of new topics.
  • Do not start any completely new chapter today.
  • Practice writing balanced chemical equations neatly.
  • Revise diagrams like electrochemical cells and organic mechanisms.
  • Read textbook in-text and back exercise questions carefully.
  • Sleep on time and keep your mind calm before the exam.

• Feb 17, 2026 07:40 AM IST

  SN1 vs SN2 Reaction

  SN1	SN2
  Two-step	One-step
  Forms carbocation	No carbocation
  Rate depends on 1 reactant	Rate depends on 2 reactants

• Feb 17, 2026 07:20 AM IST

  Molarity vs Molality

  Molarity (M): Moles of solute per litre of solution. Depends on temperature.

  Molality (m): Moles of solute per kg of solvent. Does not depend on temperature.

• Feb 17, 2026 07:00 AM IST

  Organic Chemistry Rapid Fire Questions for Revision

  1. Aldehyde group is –CHO at which position?
  2. SN2 reaction: one-step or two-step?
  3. Markovnikov rule: H adds to carbon with more or fewer hydrogens?
  4. Nucleophile: electron-rich or electron-deficient?
  5. Ketone: carbonyl at end or middle of chain?

• Feb 17, 2026 06:40 AM IST

  Inorganic Chemistry Rapid Fire Questions for Revision

  1. Ligand attached through two or more donor atoms is called?
  2. Lanthanoids belong to which series?
  3. Complex salt - completely dissociates in water or not?
  4. Heteroleptic complex contains how many types of ligands?
  5. Difference between allotropy and isomerism?

• Feb 17, 2026 06:20 AM IST

  Physical Chemistry Rapid Fire Questions for Revision

  1. Moles of solute per litre of solution is called?
  2. Molecularity of a reaction is always theoretical or experimental?
  3. Strong electrolyte - completely or partially ionizes?
  4. What does the rate of reaction depend on in an SN1 reaction?
  5. Which cell converts chemical energy into electrical energy?

• Feb 17, 2026 06:00 AM IST

  Maharashtra HSC Chemistry Exam 2026 Hall Ticket

  Check your Hall Ticket now. Ensure the photo and signature are clear. Keep it in your exam bag with a valid ID.

  
   

• Feb 17, 2026 05:00 AM IST

  Important Numerical from Solutions Chapter

  Question: A mixture of benzene and toluene contains 30% by mass of toluene. At 30°C, vapour pressure of pure toluene is 36.7 mmHg and that of pure benzene is 118.2 mmHg. Assuming that the two liquids form ideal solution, calculate partial pressure of each constituent in the above solution at 30°C.

  Answer: 

  Given:

  Mass % of toluene = 30%
  Mass % of benzene = 70%

  Vapour pressure of pure toluene (P°ₜ) = 36.7 mmHg
  Vapour pressure of pure benzene (P°ᵦ) = 118.2 mmHg

  Temperature = 30°C

  Step 1: Assume total mass of solution = 100 g

  Mass of toluene = 30 g
  Mass of benzene = 70 g

  Step 2: Calculate number of moles

  Molar mass:

  Benzene (C₆H₆) = 78 g/mol
  Toluene (C₇H₈) = 92 g/mol

  Moles of toluene:

  nₜ = 30 / 92 = 0.326 mol

  Moles of benzene:

  nᵦ = 70 / 78 = 0.897 mol

  Step 3: Calculate mole fraction

  Total moles = 0.326 + 0.897 = 1.223 mol

  Mole fraction of toluene:

  Xₜ = 0.326 / 1.223 = 0.267

  Mole fraction of benzene:

  Xᵦ = 0.897 / 1.223 = 0.733

  Step 4: Apply Raoult’s Law

  Raoult’s Law:

  P = X × P°

  Partial pressure of toluene:

  Pₜ = 0.267 × 36.7
  Pₜ = 9.80 mmHg

  Partial pressure of benzene:

  Pᵦ = 0.733 × 118.2
  Pᵦ = 86.64 mmHg

  Final Answer

  Partial pressure of toluene = 9.80 mmHg

  Partial pressure of benzene = 86.64 mmHg

• Feb 17, 2026 03:00 AM IST

  Important Questions of Ionic Equilibrium

  1. Explain ‘common ion effect’ with example.
  2. Derive Ostwald’s dilution law for weak acid. Obtain relation between solubility product and its solubility for Al(OH)3.
  3. Write the name of buffer which is used to maintain pH of 8 to 10 for precipitation of cations of III A group in qualitative analysis
  4. If ‘S’ is solubility in mol dm and ksp is the solubility product. Then write the relation between them for the CaF2 and BaSO4
  
   

• Feb 17, 2026 02:00 AM IST

  Important Questions of Solid State

  1. Define a unit cell.
  2. Which colour is shown by NaCl crystal due to formation of F-centre?
  
   

• Feb 17, 2026 01:00 AM IST

  Important Questions of Organic Chemistry

  1. Explain optical activity in 2-chlorobutane.
  2. Write structural formula for methyl vinyl ether.
  3. Explain Aldol condensation reaction of ethanal.
  4. Write note on Reimer-Tiemann reaction.
  
   

• Feb 17, 2026 12:00 AM IST

  Important Questions of Chemistry in Everyday Life

  1. Write full name of DDT.
  2. What are antacids? Give one example.
  3. Differentiate between analgesics and antipyretics.
  4. What are antiseptics and disinfectants? Explain with suitable examples.
  
   

• Feb 16, 2026 11:00 PM IST

  Important Questions of Chemical Thermodynamics

  1. State whether the reaction is spontaneous or non-spontaneous if ΔH = 50 kJ and ΔS = –130 J K⁻¹ at 250 K.
  2. State whether entropy change is positive or negative: (i) Melting of ice (ii) Vaporisation of a liquid

• Feb 16, 2026 10:40 PM IST

  Important Questions of Coordination Compounds

  1. Explain the formation of [Co(NH₃)₆]³⁺ ion on the basis of Valence Bond Theory.
  2. Define Co-ordination number.
  3. Write one example of each of ionisation, linkage and hydrated isomerism.
  4. Explain the formation of [Co(NH₃)₆]³⁺ ion on the basis of Valence bond theory. Convert the following: (a) acetic acid to ethyl acetate (b) acetic acid to ethyl alcohol.
  
   

• Feb 16, 2026 10:20 PM IST

  Chemical Reaction to Phenol to Cyclohexanol

  Phenol can be converted into cyclohexanol by hydrogenation.

  C₆H₅OH + 3H₂ → C₆H₁₁OH

  (Phenol) → (Cyclohexanol)

  
   

• Feb 16, 2026 10:00 PM IST

  Chemical Reaction to Convert Phenol to Benzoquinone

  Phenol can be converted into p-benzoquinone by oxidation.

  Phenol + [O] → p-Benzoquinone

  Chemical change:

  C₆H₅OH → C₆H₄O₂

  
   

• Feb 16, 2026 09:40 PM IST

  Features of SN2 Mechanism

  SN2 means Substitution Nucleophilic Bimolecular. It is a type of nucleophilic substitution reaction. Given below are the main features for your understanding:

  1. The reaction happens in a single step. There is no intermediate formed.
  2. The rate depends on both the alkyl halide and the nucleophile.
     Rate = k [Alkyl halide][Nucleophile]
  3. The nucleophile attacks from the opposite side of the leaving group.
  4. If the carbon is chiral, the product shows inversion. This is called Walden inversion.
  5. A high-energy transition state is formed where the carbon is partially bonded to both nucleophile and leaving group.
  6. Reactivity order:
     Primary > Secondary >> Tertiary
     Tertiary rarely undergo SN2 because of steric hindrance.
  7. Strong nucleophiles like OH⁻, CN⁻, I⁻ favor SN2 needed.

• Feb 16, 2026 09:20 PM IST

  Aldol Condensation Reaction of Ethanal

  The aldol condensation of ethanal is a reaction where two molecules of ethanal react in the presence of a dilute base to form a bigger molecule.

  Step 1: Aldol Formation

  When ethanal (CH₃CHO) is treated with dilute NaOH, two molecules combine to form a compound called aldol.

  Reaction:

  2 CH₃CHO → CH₃–CH(OH)–CH₂–CHO

  The product formed is 3-hydroxybutanal, commonly called aldol.

  This step is called aldol addition because:

  • One molecule forms an enolate ion
  • It attacks another ethanal molecule
  • A β-hydroxy aldehyde is formed

  Step 2: Condensation (On Heating)

  When the aldol is heated, it loses a water molecule (dehydration).

  CH₃–CH(OH)–CH₂–CHO → CH₃–CH=CH–CHO + H₂O

  The final product is but-2-enal (crotonaldehyde).

• Feb 16, 2026 09:00 PM IST

  What is Reimer-Tieman reaction?

  The Reimer-Tiemann reaction is a chemical reaction used to introduce a -CHO group (aldehyde group) into a phenol ring. It converts phenol into salicylaldehyde using chloroform and a base.

  Reaction Conditions

  • Reactant: Phenol
  • Reagent: Chloroform (CHCl₃)
  • Base: Sodium hydroxide (NaOH)
  • Medium: Basic medium
  • Followed by: Acidic workup

  General Reaction

  Phenol + CHCl₃ + NaOH → o-hydroxybenzaldehyde (salicylaldehyde)

  Example

  When phenol reacts with chloroform in the presence of NaOH, an aldehyde group (-CHO) is introduced at the ortho position of the benzene ring.

  Main product: Salicylaldehyde (o-hydroxybenzaldehyde)
  Minor product: p-hydroxybenzaldehyde

• Feb 16, 2026 08:40 PM IST

  Important 3/4-Mark/MCQ Questions of HCS Chemistry Solutions Chapter

  • Derive the expression for molar mass of solute in terms of boiling point elevation of solvent.
  • Explain the phenomenon of osmosis with a suitable diagram. 
  • Explain with the help of vapor pressure-temperature curves for solution and solvent, why boiling point of solvent is elevated when a nonvolatile solute is dissolved into it.
  • What are non-ideal solutions? Explain with reasons and diagrams the positive and negative deviations from Raoult’s law shown by non-ideal solutions. 
  • Explain with vapor pressure-temperature curves that the freezing point of a solvent is lowered by dissolving a nonvolatile solute into it. Give a reason for such lowering of freezing of solvent. Definefollowing terms a) Reverse Osmosis b) Semi permeable membrane c) Osmotic pressure d) Isotonic solution.

• Feb 16, 2026 08:20 PM IST

  Important 2-Mark/MCQ Questions of HCS Chemistry Solutions Chapter

  • For a very dilute solution, the osmotic pressure is given by π =?2 ??/? where V is the volume in L containing n2 moles of nonvolatile solute. Establish the equation for molar mass of solute.
  • Distinguish between ideal and non-ideal solutions. 
  • Write two points to explain why vapor pressure of solvent is lowered by dissolving nonvolatile solute into it. 
  • In what way Kf and Kb are similar and in what way they are different? 
  • Calculate total moles after dissociation in 0.1M KCl solution and 0.05M aluminum sulphate solution.Which of the two solutions will have higher freezing point depression.

• Feb 16, 2026 08:00 PM IST

  Important 1-Mark/MCQ Questions of HCS Chemistry Solutions Chapter

  • Sugar dissolves in water because..?
  • The units of Henry’s law constant are..?
  • Which of the following solutions /solvent has maximum vapor pressure?
  • What are hypertonic solutions? 
  • What is cryoscopic constant? 
  • Write the effect of dissolution of a nonvolatile solute on the freezing point of solvent. 
  • Write the expression for relative lowering of vapor pressure.

• Feb 16, 2026 07:40 PM IST

  HCS Chemistry BCC vs FCC Unit Cell

  Basis of Comparison	BCC (Body-Centered Cubic)	FCC (Face-Centered Cubic)
  Full Form	Body-Centered Cubic	Face-Centered Cubic
  Arrangement of Atoms	8 atoms at corners + 1 atom at center	8 atoms at corners + 6 atoms at faces
  Number of Atoms per Unit Cell	2	4
  Coordination Number	8	12
  Atomic Packing Factor (APF)	0.68 (68%)	0.74 (74%)
  Packing Efficiency	Less dense	More dense
  Edge Length Relation (r = atomic radius)	a = 4r / √3	a = 2√2 r
  Structure Type	Not closely packed	Closely packed
  Examples	Iron (Fe), Chromium (Cr), Tungsten (W)	Copper (Cu), Aluminum (Al), Silver (Ag), Gold (Au)

• Feb 16, 2026 07:20 PM IST

  What is the “common ion effect”?

  The common ion effect is when the ionization of a weak acid or weak base gets reduced because you add another substance that already has one of the same ions.

  Simply put, if a solution already has a particular ion, adding more of the same ion makes the weak acid or base break apart less.

  Take acetic acid for example. Its formula is CH₃COOH. In water, it breaks a little into:

  CH₃COOH ⇌ CH₃COO⁻ + H⁺

  Now, if you add sodium acetate (CH₃COONa) to this solution, it gives more CH₃COO⁻ ions.

  Since CH₃COO⁻ is already present, the acid will break apart even less. This decrease in ionization is called the common ion effect.

• Feb 16, 2026 07:00 PM IST

  Few Important 3/4-Mark Questions on Solid State

  • Calculate the packing efficiency for bcc lattice. 
  • In case of HCP structure, how are spheres in the first, second and third layers arranged? 
  • A substance crystallises in an fcc structure. The unit cell edge length is 367.8pm. Calculate the molar mass of the substance if its density is 21.5 g/cm3
  • What are non-stoichiometric point defects? Explain with a diagram the formation of F-centres.
  • Write the classification of stoichiometric point defects. What is a substitutional impurity defect? Explain solid solutions of metals and vacancies through aliovalent cations. 
  • Derive the relationship between the density of a substance, its molar mass and the unit cell edge length. Explain how you will calculate the number of particles and number of unit cells in x g of metal.

• Feb 16, 2026 06:40 PM IST

  Few Important 2-Mark Questions on Solid State

  • Explain the terms: a) Isomorphism b) Polymorphism, with examples 
  • Classify the following solids as molecular, ionic, covalent and metallic solids. Pb, MgF2, SO2 and quartz 
  • Explain the vacancy defect with a diagram. 
  • Calculate the number of unit cells in 0.3 g of a species having a density of 8.5 g/cm3 and a unit cell edge length of 3.25×10-8 cm.
  • When gold crystallises, it forms fcc unit cells. The unit cell edge length is 408 pm. Calculate the density of gold. Molar mass of gold is 197 g/mol. 

• Feb 16, 2026 06:20 PM IST

  Few Important 1-Mark Questions on Solid State

  • Write the effect on the density of a substance in the Frenkel defect? 
  • Write an example of a diamagnetic substance. 
  • Give one property common to both hcp and ccp crystal lattices. 
  • Write the relationship between the radius of the atom and the edge length of the fcc unit cell.
  • Draw a diagram of bcc unit cell

• Feb 16, 2026 06:00 PM IST

  Enthalpy of Atomization (ΔH°atom)

  Enthalpy of atomization is the amount of heat required to convert one mole of a substance in its standard state into its gaseous atoms.

  • It is always positive because energy is absorbed.
  • Units: kJ mol⁻¹

• Feb 16, 2026 05:40 PM IST

  Standard Enthalpy of Combustion (ΔH°c)

  Standard enthalpy of combustion is the amount of heat released when one mole of a substance is completely burned in excess oxygen under standard conditions (298 K and 1 bar pressure).

  • It is usually negative because heat is released.
  • Units: kJ mol⁻¹

• Feb 16, 2026 05:20 PM IST

  Some Important 4-Mark Questions for HSC Chemistry

  Q: (a) Distinguish between crystalline and amorphous solids. 

  (b) Explain bleaching action of chlorine in the presence of moisture. 

  Q: (a) Draw neat and labelled diagram of standard hydrogen electrode. 

  (b) Calculate e.m.f. of the following cell 

  Q:  (a) An element with molar mass 27 g/mol forms a cubic unit cell with edge length 405 pm. If the density of the crystal is 2.7 g cm–3, identify the type of unit cell. 

  (b) Derive the equation of Raoult’s law for a binary solution containing a non-volatile solute.

  Q: (a) State whether entropy change is positive or negative in the following examples : (i) Melting of ice (ii) Vaporisation of a liquid 

  (b) Explain ‘common ion effect’ with example

• Feb 16, 2026 05:00 PM IST

  Chemistry Rate Constant (k)

  Rate of reaction when concentration of each reactant is unity.

  For first order:

  The unit depends on the order of reaction.

  
   

• Feb 16, 2026 04:40 PM IST

  Order of Reaction vs Molecularity

  Basis	Order of Reaction	Molecularity
  Definition	Sum of powers of concentration in rate law	Number of molecules in elementary step
  Experimental?	Yes	No
  Can be zero/fraction?	Yes	No
  Applies to	Overall reaction	Only elementary step

• Feb 16, 2026 04:20 PM IST

  Very Important Formulas for HSC Chemistry Exam

  Chemical Kinetics

  First order equation:
  k = (2.303 / t) log (a / a − x)

  Half-life (1st order):
  t½ = 0.693 / k

  Electrochemistry

  Nernst Equation:
  E = E° − (0.0591 / n) log Q

  Gibbs Free Energy:
  ΔG° = − nFE°

  Solutions

  Raoult’s Law:
  P₁ = X₁P₁°

  Relative lowering of vapour pressure:
  (P° − P) / P° = X₂

  Solid State

  Density of unit cell:
  d = (Z × M) / (a³ × NA)

• Feb 16, 2026 04:00 PM IST

  Chemistry Exam Prep Last Minute Tips

  Below are some of the helpful tips for you to prepare for the upcoming chemistry exam, given by Armaann and Shivam. These two were among the toppers of HSC exam 2025:

  • 90% of the paper is derived directly from the textbook. Ignore outside notes until you've mastered every "Exercise" and "Use Your Brain Power" box.
  • Maintain a dedicated notebook for "Named Reactions" like Aldol Condensation and Reimer-Tiemann, as these are high-weightage and frequent favorites in Section D.
  • Always write the "Given Data," the formula, and the final answer with correct units to ensure partial marks even if the calculation comes out to be wrong at the end.
  • You can get easy marks by being thorough with definitions and formulas, as 25% of the paper is now dedicated to MCQs and Very Short Answers.
  • Use a sharpened pencil for crystal lattices and electrochemical cells. Unlabeled or messy diagrams often result in zero marks.

• Feb 16, 2026 03:40 PM IST

  Some Important MCQ Questions for MAH HSC Chemistry

  Q: Coordination number of atoms in bcc crystal lattice is _____.
  A: 8

  Q: The unit of Henry’s Law constant is _____.
  A: mol L–1 bar–1

  Q: pH of human blood is _____.
  A: 7.4

  Q: Schottky defect is NOT observed in _____.
  A: CsCl​

  Q: The freezing point of 0.1m aqueous solution of urea, if Kf for water is 1.86 K kg mol–1 is _____. 

  A: 0.186 ºC​

  Q: Ozone layer is depleted by _____.
  A: chlorofluorocarbons (CFCs)

  Q: Integrated rate law equation for a zero-order reaction is
  A: [A] = [A]₀ - kt

  Q: The spin only magnetic moment of Fe²⁺ ion is ____.
  A: 4.90 BM

  Q: The relation between radius of sphere and edge length in simple cubic lattice is ____.
  A: r = a/2

• Feb 16, 2026 03:20 PM IST

  Maharashtra HSC Chemistry 2026 Expected Difficulty Level

  The Chemistry exam for 2026 is expected to have an easy to moderate difficulty level, similar to the 2025 paper, which had easy objective and very short answers, moderate short answers, and easy-to-moderate long answers, with organic chemistry as the toughest section, followed by physical and inorganic.

• Feb 16, 2026 03:00 PM IST

  HSC Chemistry Question-Wise Weightage

  Section	Type of Questions	Number of Questions	Marks Allotted
  A	Multiple Choice Questions	1 (has 10 subparts)	10
  	Very Short Answer Questions	1 (has 10 subparts)	8
  B	Short Answer Questions	8 (attempt any 8 out of 12)	16 (2 marks each)
  C	Short Answer Questions	8 (attempt any 8 out of 12)	24 (3 marks each)
  D	Long Answer Questions	3 (attempt any 3 out of 5)	12 (4 marks each)
  Total		31	70

• Feb 16, 2026 02:40 PM IST

  HSC Chemistry Topics Forming 4-mark Questions

  • Green Chemistry and Nanochemistry
  • Environmental Chemistry
  • Solid State Chemistry
  • Electrochemistry
  • Thermodynamics
  • Organic Chemistry
  • Coordination Chemistry
  • p-Block Elements
  • Solutions
  • Chemical Kinetics
  • Polymers
  • General Principles and Processes of Isolation of Elements

• Feb 16, 2026 02:20 PM IST

  Maharashtra HSC Chemistry 2026 Chapter-Wise Weightage

  Unit	Marks without Option	Marks with Option
  Solid State	04	06
  Solutions and Colligative Properties	05	07
  Chemical Thermodynamics and Energetics	06	08
  Electrochemistry	05	07
  Chemical Kinetics	04	06
  General Principles and Processes of Isolation of Elements	03	05
  p-Block Elements	08	10
  d and f – Block Elements	05	06
  Coordination Compounds	03	04
  Halogen Derivatives of Alkanes and Arenes	04	06
  Alcohols, Phenols, and Ethers	04	06
  Aldehydes, Ketones and Carboxylic Acids	05	07
  Compounds Containing Nitrogen	04	06
  Biomolecules	04	06
  Polymers	03	04
  Chemistry in Everyday Life	03	04

• Feb 16, 2026 02:00 PM IST

  HSC Chemistry High-Weightage Topics

  • Chemical Thermodynamics 
  • p-Block Elements
  • Aldehydes, Ketones and Carboxylic Acids
  • Electrochemistry 
  • Chemical Kinetics

• Feb 16, 2026 04:00 AM IST

  What are monosaccharides?

  Monosaccharides are the simplest carbohydrates which cannot be hydrolysed into smaller carbohydrate units. They are basic building units of carbohydrates.

  They are polyhydroxy aldehydes or ketones containing one aldehyde group or one ketone group along with multiple hydroxyl groups.

  They are also called simple sugars.

  General formula: , where n ranges from 3 to 7

  Examples: Glucose, fructose, and ribose.

  Monosaccharides are sweet in taste, soluble in water, and are reducing sugars.