Moving Between CBSE and ICSE — What Changes in Chemistry
A transfer, a father's posting, a move to another city, a school change after Class 10 — every year a large number of students change board mid-way. The chemistry does not change, because chemistry is chemistry. What changes is the order topics were taught in, the depth they were taught to, and the style of question the new board asks.
The danger is not the difficulty. It is that a gap in one specific area sits quietly for months until it blocks a whole chapter. This article gives you a way to find that gap in a weekend instead of finding it in an exam.
The rule that matters more than any comparison table
Syllabus documents are revised. Any specific chapter list printed on a website, in a guide book, or in a WhatsApp forward may be from an older revision. The board publishes the current curriculum for each class; your school office or subject teacher can put the correct document in your hands. Ten minutes with the real document beats an hour of second-hand advice.
The structural differences that are safe to plan around
At the secondary stage the two systems package science differently, and that packaging alone changes how you must study.
| What to check | Why it changes your study |
|---|---|
| Is chemistry examined as its own paper, or inside a combined Science subject? | A separate chemistry paper usually means longer answers and more chemistry-specific question types. A combined paper means chemistry competes for time with physics and biology on the same day. |
| How much of the assessment is internal or practical? | Practical files, project work and internal marks are earned across the year and cannot be recovered by studying harder in March. Find out what counts in your new school in your first week. |
| Question style in the last few years' papers | The fastest read on a board is its own past papers. Reasoning questions, equation writing, numericals and structured long answers are weighted differently, and your answer-writing habit has to follow. |
| Prescribed textbook and reference | The textbook is not a detail. Board questions are usually framed in the vocabulary of the prescribed book, and using another book's terminology can cost marks even when the chemistry is right. |
| Order of chapters within the year | This is where mid-year transfers get hurt: your new class may already have finished a chapter your old school had scheduled for next term. |
The weekend diagnostic — find the gap in four hours
Do not try to "revise everything from the other board". Instead, test yourself on the small number of skills that everything else in Class 9–12 chemistry is built on. If these are solid, a chapter-order difference is a nuisance. If one of them is missing, it will block you repeatedly.
- Writing and balancing equations, including ionic equations.
- The mole concept — mass to moles, moles to particles, moles to volume.
- Relative molecular mass and vapour density.
- Concentration — molarity, and whatever concentration language your new textbook uses.
- Basic organic naming up to the level your new class has reached.
- Reading and using the periodic table for trends rather than as a list.
Give each one a short set of questions from the new board's own textbook. Whatever you cannot do is your gap, and it is almost always item 2 or item 3.
Worked example 1 — vapour density to molar mass
Vapour density appears in some syllabi early and in others barely at all, so this is a classic transfer gap. The relationship is short and exact:
Question: A gas has vapour density 22. What is its molar mass, and what could the gas be?
Step 1. M = 2 × VD = 2 × 22 = 44 g/mol
Step 2 — identify. Test CO₂:
C: 1 × 12.011 = 12.011
O: 2 × 15.999 = 31.998
M(CO₂) = 12.011 + 31.998 = 44.009 g/mol — a match.
Note that propane, C₃H₈, also comes to 3 × 12.011 + 8 × 1.008 = 36.033 + 8.064 = 44.097 g/mol. Molar mass alone does not identify a substance; it narrows the candidates, and a second piece of evidence decides. Writing that sentence in an answer is often worth a mark on its own.
Worked example 2 — the mole, including the STP that two books disagree about
Question: Find the number of moles in 5.6 g of nitrogen gas, and the volume it occupies at STP.
Step 1 — molar mass. N = 14.007, and nitrogen gas is N₂:
M(N₂) = 2 × 14.007 = 28.014 g/mol
Step 2 — moles.
n = mass ÷ molar mass = 5.6 ÷ 28.014 = 0.19990 ≈ 0.200 mol
Step 3 — volume at STP. Two answers exist, and which one is correct depends on which STP your book defines:
- Older convention, 0 °C and 1 atm, molar volume 22.4 L/mol: V = 0.200 × 22.4 = 4.48 L
- Current IUPAC convention, 0 °C and 1 bar, molar volume 22.7 L/mol: V = 0.200 × 22.7 = 4.54 L
Both are right under their own definition. When you change board or change textbook, check which one your new book uses and state the value you used in your answer. Examiners accept a stated convention; they cannot accept an unexplained number.
A four-week catch-up plan after a transfer
| Week | Focus | Test of success |
|---|---|---|
| 1 | Get the current syllabus document and the new prescribed textbook. Run the weekend diagnostic. List gaps. | You have a written list of two or three specific gaps, not a feeling of being behind |
| 2 | Close the biggest gap only. Usually the mole concept or equation work. | You can do the new textbook's exercises on that topic unaided |
| 3 | Read the chapters your new class has already finished — from the new book, not the old one. | You can answer the new book's in-chapter questions on those chapters |
| 4 | One past paper of the new board, timed. Match your answer style to its marking style. | You know how long its answers are meant to be, and you finished in time |
Notice that keeping up with current class work continues throughout. The catch-up sits beside it, not instead of it — a student who stops attending to today's chapter in order to fix last term's simply creates next term's gap.
What goes wrong after a board change
- Studying from the old board's textbook out of familiarity. The chemistry may be the same, but the vocabulary, symbols and expected answer length are not. Switch to the prescribed book immediately.
- Assuming the new board is "easier" or "harder". They are different in emphasis. Believing one is easier leads to a relaxed first term and a bad first report.
- Ignoring internal assessment, practicals and project work. These accumulate quietly from day one and cannot be recovered later.
- Trying to re-study two years of the previous syllabus. Unnecessary, and it consumes the hours current work needs. Fix the diagnosed gaps only.
- Not asking the subject teacher what has already been covered. One five-minute conversation in your first week replaces months of guessing.
- Mixing conventions mid-answer — 22.4 L/mol in one line and 22.7 L/mol in the next, or a textbook symbol from the old board. Pick the new book's convention and state it.
The reassuring part
Board syllabi at Class 11 and 12 converge far more than they diverge, because both are preparing students for the same higher-education entry. Mole concept, atomic structure, bonding, equilibrium, thermodynamics, electrochemistry, coordination compounds and the standard organic chapters appear in both. A transfer is a re-sequencing problem, not a re-learning problem, and the students who suffer are the ones who never diagnosed exactly which sequence they lost.
The mole is where most transfer gaps sit — check your working instantly. The Molar Mass & Composition calculator takes any formula, from N₂ and CO₂ to CuSO₄·5H₂O, and returns the molar mass with the element-by-element breakdown, so the diagnostic above can be self-marked in one sitting.
Open the Molar Mass Calculator →If a board change has left a specific hole in Class 11–12 chemistry, that is exactly the kind of gap teaching fixes faster than self-study. ABC Chemistry runs Class 11–12 chemistry at its Gurugram centre and online across India — abcchemistry.in. Families in Delhi, Noida and Gurgaon who would rather close the gap one-to-one at home can look at delhihometutor.com.