What the board asks
We went through the ISC board papers, question by question, and matched each question to a topic. Here is what was asked, how often, and what was never asked.
Computer Science: 180 topics in the 2027 syllabus, across 10 units. The board has asked 117 of them at least once. 63 were never asked in the papers we checked.
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CS1 Boolean Algebra
All the topics in Computer Science: Boolean Algebra
Asked topics first, the most asked at the top. Tap a topic to see what to write, the result, the years, and the real board questions.
27 topics shown
| # | Topic | Type | Marks | Times asked | Last asked | Status |
|---|---|---|---|---|---|---|
| 1 | Principle of duality: state it and write the dualState the principle, or write the dual of a given Boolean equation by swapping + with . and 0 with 1 on both sides, leaving variables and their complements unchanged. | Sum | 1 | 9 papers | 2026 | Asked |
| 2 | Complement of an expression using De Morgan's theoremApply De Morgan's theorem step by step to write F' for a given expression, swapping + and . and complementing each literal, and simplify if asked. | Sum | 1 | 9 papers | 2026 | Asked |
| 3 | Word problem to truth table and SOP or POSRead the conditions, draw the 16-row truth table for the four named inputs in the stated order with the output column, and write the canonical SOP (from 1s) or POS (from 0s) as asked, in cardinal or canonical form. | Sum | 5 | 9 papers | 2026 | Asked |
| 4 | K-map reduction of a four-variable POS expressionDraw the 4x4 map with Gray-code labels, place the 0s for the maxterms, ring and label octets, quads and pairs, and write the reduced POS with one sum term per group. | Sum | 4 | 9 papers | 2026 | Asked |
| 5 | K-map reduction of a four-variable SOP expressionDraw the 4x4 map with Gray-code labels, place the 1s for the minterms, ring and label octets, quads and pairs with no redundant group, and write the reduced SOP. | Sum | 4 | 8 papers | 2025 improvement | Asked |
| 6 | Truth table to classify tautology, contradiction or contingencyDraw the complete truth table with an intermediate column for each sub-expression and a final column, then state the classification with the reason from the final column. | Sum | 2 | 6 papers | 2026 | Asked |
| 7 | Convert between cardinal and canonical formsTurn a cardinal list sigma(...) or pi(...) into its canonical SOP or POS expression, or a canonical expression or single term (m3, M5) into cardinal form, showing the binary of each index. | Sum | 2 | 6 papers | 2025 improvement | Asked |
| 8 | State and identify Boolean postulates and theoremsState the law asked in its two dual forms (or name the law shown): properties of 0 and 1, idempotence, commutative, associative, distributive, complement, absorption, involution, De Morgan. | Statement | 1 | 5 papers | 2026 | Asked |
| 9 | Logic gate diagram for a reduced SOP or POSDraw the AND-OR (for SOP) or OR-AND (for POS) circuit for the reduced expression, taking variables and complements as inputs, with each gate's output labelled. | Diagram | 1 | 5 papers | 2026 | Asked |
| 10 | Converse, inverse and contrapositive of an implication in symbolsFor a given implication p => q (often with negations), write the converse, inverse and contrapositive in symbols, or pick the right option or judge an Assertion-Reason item. | Statement | 1 | 5 papers | 2025 improvement | Asked |
| 11 | Simplify a Boolean expression using Boolean lawsReduce the given expression to its simplest form, one law per line, naming the law used at each step. | Sum | 2 | 5 papers | 2024 | Asked |
| 12 | Define minterm and maxterm; write them for given valuesDefine minterm and maxterm, and for a given set of variable values write the minterm (product, 0 -> complemented) and the maxterm (sum, 1 -> complemented). | Statement | 1 | 3 papers | 2026 | Asked |
| 13 | Truth table to verify an equivalence or validityDraw one truth table holding both sides of the given proposition (or the whole formula), with intermediate columns, and conclude from identical columns (or an all-1 column) that it is or is not valid. | Sum | 2 | 3 papers | 2025 improvement | Asked |
| 14 | Truth table to prove a Boolean lawName the law, then draw a truth table with columns for each side (and intermediate terms) and conclude that the two final columns are identical. | Sum | 1 | 3 papers | 2023 | Asked |
| 15 | State and recognise the equivalence laws of propositional logicState the law named (or name the law shown) in symbols: commutative, associative, distributive, De Morgan, implication, biconditional, identity, negation, excluded middle, contradiction, and judge Assertion-Reason items that use them. | Statement | 1 | 2 papers | 2026 | Asked |
| 16 | Converse, inverse, contrapositive as English sentencesGiven two simple statements and an implication between them, write the requested converse, inverse or contrapositive as a full 'If ..., then ...' sentence. | Statement | 1 | 2 papers | 2026 | Asked |
| 17 | Prove a Boolean identity using laws, naming each lawTransform the left side into the right side (often 1 or 0) one step at a time, writing the name of the law used against every step. | Sum | 3 | 2 papers | 2026 | Asked |
| 18 | Canonical SOP or POS from a truth tableFrom a given truth table (or a connective such as A <=> B) write the canonical SOP from the 1-rows or the canonical POS from the 0-rows. | Sum | 1 | 2 papers | 2025 | Asked |
| 19 | Reduced K-map expression drawn with NAND or NOR onlyDraw the circuit for the reduced SOP using NAND gates only, or the reduced POS using NOR gates only, with variables and complements as inputs. | Diagram | 2 | 2 papers | 2025 improvement | Asked |
| 20 | Expand an SOP or POS expression to canonical formFor each term missing a variable, multiply by (x + x') in SOP or add x.x' in POS, expand, remove repeated terms and write the canonical SOP or POS. | Sum | 2 | 2 papers | 2018 | Asked |
| 21 | Prove chain rule or modus ponens using lawsStarting from the given wff, rewrite every => as ~p OR q, then apply De Morgan, distributive, complement and absorption steps, one law per line with its name, until the expression becomes true (1) or the required form. | Sum | 3 | 1 paper | 2026 | Asked |
| 22 | Gray code, K-map layout and grouping rulesExplain Gray code and why K-map rows and columns use it, label 2-, 3- and 4-variable maps with cell numbers, and state the grouping rules (powers of 2, wrap-round, largest groups, no redundant group). | Statement | 1 | 1 paper | 2026 | Asked |
| 23 | Define proposition, wff, tautology, contradiction, contingencyWrite a one- or two-line definition of each term asked (proposition, connective, wff, tautology, contradiction, contingency, satisfiable, unsatisfiable, valid) with a tiny example, or state the difference between two of them. | Statement | 1 | 1 paper | 2025 improvement | Asked |
| 24 | Write a word statement as a wffAssign a propositional variable to each simple statement, then write the compound sentence as a wff using ~, AND, OR, =>, <=> with correct brackets. | Sum | 1 | never | Never asked | |
| 25 | Truth table of a compound proposition (all connectives)Build the full truth table for a wff in two or three variables, with one column for each sub-expression, using the truth tables of ~, AND, OR, =>, <=>. | Sum | 1 | never | Never asked | |
| 26 | Truth tables for half adder, full adder, majority circuitWrite the inputs and outputs, draw the truth table and derive the SOP for each output (sum, carry, majority). | Sum | 2 | never | Never asked | |
| 27 | K-map reduction of a two- or three-variable expressionDraw the 2x2 or 2x4 map with Gray-code labels, place the terms, group and write the reduced SOP or POS. | Sum | 2 | never | Never asked |
This list was made from the 2027 syllabus and checked with 9 board papers, including the 2027 specimen paper. It is not yet checked with the textbook.
The 10 topics Computer Science papers ask most
Counted on the board papers from 2018 to the 2027 specimen paper, which every unit has been checked against.
- 1.Principle of duality: state it and write the dualCS1 Boolean Algebra · asked 8 times since 2018
- 2.Complement of an expression using De Morgan's theoremCS1 Boolean Algebra · asked 8 times since 2018
- 3.Word problem to truth table and SOP or POSCS1 Boolean Algebra · asked 8 times since 2018
- 4.K-map reduction of a four-variable POS expressionCS1 Boolean Algebra · asked 8 times since 2018
- 5.Pre-order, in-order and post-order traversalCS9 Data Structures · asked 8 times since 2018
- 6.K-map reduction of a four-variable SOP expressionCS1 Boolean Algebra · asked 7 times since 2018
- 7.Read a tree: leaves, internal nodes, parent, siblings, degreeCS9 Data Structures · asked 7 times since 2018
- 8.Truth table to classify tautology, contradiction or contingencyCS1 Boolean Algebra · asked 6 times since 2018
- 9.Convert between cardinal and canonical formsCS1 Boolean Algebra · asked 6 times since 2018
- 10.Address of an element, row major and column majorCS6 Arrays and Strings · asked 6 times since 2018