Ultimate study guide and exam advice for Cambridge IGCSE Chemistry (0620), compiling actual examiner insights, critical structural pitfalls, and highly high-yield topic blueprints from the 2023-2025 syllabus.
อ่าน 4 นาทีอัปเดตเมื่อ: 21 มิ.ย. 2569
ภาพรวมข้อสอบ
จำนวนฉบับ
3
คะแนนเต็ม
160
เวลาสอบ
3ชม.
ประเภทคำถาม
3
ฉบับ
เวลา
คะแนน
จำนวนข้อ
น้ำหนักคะแนน
ประเภทคำถาม
Paper 2 Multiple Choice (Extended)
45นาที
40
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Paper 4 Theory (Extended)
1ชม. 15นาที
80
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Paper 6 Alternative to Practical
1ชม.
40
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เกณฑ์เกรด
A*ABCDEFGU
ข้อกำหนดเครื่องคิดเลข
A silent scientific calculator may be used on papers where calculators are permitted (some papers are non-calculator). It must not be graphical or programmable and must hold no stored information.
วัตถุประสงค์: Tabulate \(y\) across a range of \(x\) to locate sign changes (roots) and approximate maxima/minima.
ใช้เมื่อใด: Solving or sketching a function when you want to find where its graph crosses or turns.
ขั้นตอน
Enter the function in TABLE mode, set the start, end and step, then read where the sign of \(y\) changes or where it peaks.
ข้อควรระวังในการสอบ: Allowed on papers where a calculator is permitted; use a silent scientific calculator with no stored content and show your method.
Statistics mode (mean, SD & regression)
Scientific calculator (e.g. Casio fx-991 series)
วัตถุประสงค์: Read the mean \(\bar{x}\) and standard deviation directly, and the gradient/intercept (and \(r\)) of a linear regression for bivariate data.
ใช้เมื่อใด: Any data-handling, statistics, or required-practical analysis question.
ขั้นตอน
Enter the data in STAT mode (1-VAR or A+BX), then recall \(\bar{x}\), \(\sigma\) or the regression coefficients.
ข้อควรระวังในการสอบ: Allowed on papers where a calculator is permitted; use a silent scientific calculator with no stored content and show your method.
Carry exact values with Ans & memory
Scientific calculator (e.g. Casio fx-991 series)
วัตถุประสงค์: Keep full-precision intermediate values to avoid rounding errors.
ใช้เมื่อใด: Multi-step calculations where premature rounding loses the final accuracy mark.
ขั้นตอน
Use Ans, STO/RCL or the M+ memory to reuse the unrounded result of each step; round only the final answer.
ข้อควรระวังในการสอบ: Allowed on papers where a calculator is permitted; use a silent scientific calculator with no stored content and show your method.
Equation solver — to CHECK your working
Scientific calculator (e.g. Casio fx-991 series)
วัตถุประสงค์: Use the built-in EQN/SOLVE mode to verify roots of quadratics or simultaneous equations you have already solved by algebra.
ใช้เมื่อใด: As a check only, after solving by hand.
ขั้นตอน
Enter the coefficients in EQN mode (or use SOLVE) and confirm they match your worked solution.
ข้อควรระวังในการสอบ: Allowed on papers where a calculator is permitted; use a silent scientific calculator with no stored content and show your method.
ข้อผิดพลาดที่พบบ่อย
1highคะแนนที่เกี่ยวข้อง: 2Formulae, functional groups and terminology (Organic chemistry)
Omitting the single covalent bond line between oxygen and hydrogen (O-H) in displayed organic formulas.
วิธีหลีกเลี่ยง: Always show every single bond explicitly as '-O-H' instead of '-OH' when drawing fully displayed structures of alcohols, carboxylic acids, or esters.
2mediumคะแนนที่เกี่ยวข้อง: 1Extraction of metals (Metals)
Stating that cryolite acts as a catalyst or lowers the melting point of alumina in the extraction of aluminium.
วิธีหลีกเลี่ยง: Specify that cryolite acts as a solvent to dissolve aluminium oxide, reducing the operational processing temperature.
3highคะแนนที่เกี่ยวข้อง: 2Preparation of salts (Acids, bases and salts)
Omitting state symbols in chemical and ionic equations representing precipitation reactions.
วิธีหลีกเลี่ยง: Always label dissolved ionic reactants as (aq) and the resulting insoluble precipitate as (s) (e.g., BaSO4(s)).
4mediumคะแนนที่เกี่ยวข้อง: 1Exothermic and endothermic reactions (Chemical energetics)
Omitting the positive (+) or negative (-) signs in enthalpy change calculations and oxidation numbers.
วิธีหลีกเลี่ยง: Always prefix enthalpy values with '-' for exothermic or '+' for endothermic reactions, and include correct signs for oxidation states (e.g., '+6' instead of '6').
5highคะแนนที่เกี่ยวข้อง: 2Reversible reactions and equilibrium (Chemical reactions)
Stating that a catalyst shifts the position of dynamic equilibrium or increases the final yield of products.
วิธีหลีกเลี่ยง: Explain that a catalyst only increases the rate of both forward and reverse reactions equally, speeding up how fast equilibrium is reached without changing the yield.
6highคะแนนที่เกี่ยวข้อง: 2Experimental design (Experimental techniques and chemical analysis)
In planning questions, forgetting to wash and dry the collected residue before weighing it.
วิธีหลีกเลี่ยง: Always include a step to wash the filtered residue with distilled water and dry it in a warm oven or with filter paper to achieve a constant mass.