Step-by-step ICSE solutions and marking scheme for Sound from Selina Concise Physics (Class 8) - Chapter 7 and 5 generated practice problem sets.

ICSE Class 8 Physics: Sound Solved Exercises & 5 Generated Exam Problems

📘 Prescribed Textbook Solved Exercise (Selina Concise Physics (Class 8))

Primary Curriculum Benchmark

Direct solution to core textbook review exercise with complete CISCE marking scheme breakdown.

Textbook Exercise 7 - Section Numerical Q.6 Selina Concise Physics (Class 8) - Chapter 7 - Chapter 7 Exercises

3 Marks Allotted

A physical system operates under the principles of Sound. (i) State the underlying physical law. (ii) Calculate the primary physical quantity when subjected to the standard conditions of Pitch, Loudness & Quality of Sound.

Step-by-Step ICSE Evaluator Marking Key

Step 1: State the Principle & Formula

State Pitch, Loudness & Quality of Sound: Pitch depends on frequency (high pitch = shrill sound like female voice; low pitch = grave/flat sound like male voice). Loudness depends on ... Write down the governing equation.

Formula Applied: Governing Physical Law

1 Mark

Step 2: Substitute Values with SI Unit Consistency

Ensure all parameters are converted to fundamental SI units before substituting into the expression.

1 Mark

Step 3: Compute the Final Magnitude with Proper Units

Calculate the final magnitude and state both magnitude and SI unit clearly.

1 Mark

Final Verified Answer: Correctly calculated value with appropriate SI unit (Key Units: SI Units)

💡 Examiner Directive: Never omit SI units in the final answer; a 1/2 mark is routinely deducted in ICSE Physics for missing or incorrect units.

🎯 5 Generated Practice Exercises with Step-Marking

CISCE Syllabus Graded Set

Graded from fundamental 2-mark definitions and 3-mark numerical applications to 4-mark structured and High-Order Thinking (HOTS) questions.

Generated Practice Set 1 - Core Concept (2 Marks) Difficulty: Easy

2 Marks Total

Define "Pitch, Loudness & Quality of Sound" in the context of ICSE Class 8 Physics. State its primary characteristic or SI unit/standard symbol.

Step-by-Step Marking Breakdown

Step 1: Precise Technical Definition

Pitch depends on frequency (high pitch = shrill sound like female voice; low pitch = grave/flat sound like male voice). Loudness depends on amplitude of vibration and surface area....

1 Mark

Step 2: Mandatory Technical Criteria

Ensure the definition contains mandatory keywords: Pitch determined by frequency, Loudness determined by amplitude squared, Quality determined by wave-form.

1 Mark

Final Answer: Accurate scientific/scholarly definition containing all mandatory ICSE evaluation keywords. (Units: Theoretical definition)

💡 Examiner Directive: Avoid colloquial explanations. Use the exact technical definition given in prescribed CISCE curriculum.

Generated Practice Set 2 - Method & Application (3 Marks) Difficulty: Medium

3 Marks Total

Explain the procedural method or practical demonstration used to verify "Pitch, Loudness & Quality of Sound". State the working apparatus/setup and key precautions.

Step-by-Step Marking Breakdown

Step 1: State the Formula / Conceptual Principle

State the fundamental principle governing Pitch, Loudness & Quality of Sound.

1 Mark

Step 2: Mathematical / Procedural Deduction

Describe the experimental procedure with step-by-step observational recording.

1 Mark

Step 3: Concluding Result & Interpretation

Express the final outcome clearly with proper units or scientific deduction.

1 Mark

Final Answer: Verified procedural conclusion for Pitch, Loudness & Quality of Sound (Units: Procedural steps)

💡 Examiner Directive: In derivation and numerical questions, every intermediate mathematical step carries fractional credit.

Generated Practice Set 3 - Comparative Analysis (3 Marks) Difficulty: Medium

3 Marks Total

Differentiate between "Pitch, Loudness & Quality of Sound" and "Pitch, Loudness & Quality of Sound" on the basis of: (i) Fundamental definition/mechanism, (ii) Key working condition or formula, (iii) Real-world practical example or application.

Step-by-Step Marking Breakdown

Point 1: Conceptual Difference

Contrast the primary mechanisms: Pitch, Loudness & Quality of Sound focuses on Pitch determined by frequency, whereas Pitch, Loudness & Quality of Sound emphasizes Pitch determined by frequency.

1 Mark

Point 2: Quantitative / Operational Difference

Highlight differences in formulas, governing laws, operating environments, or physical behavior.

1 Mark

Point 3: Exemplary Differentiation

Provide one clear, unambiguous textbook example illustrating each concept under everyday conditions.

1 Mark

Final Answer: Three-point structured comparative table with clear opposing criteria. (Units: Tabular points)

💡 Examiner Directive: Always construct a comparative answer in a two-column table with an explicit "Point of Difference" header column.

Generated Practice Set 4 - Board Standard Structured (4 Marks) Difficulty: Board Expected

4 Marks Total

A comprehensive ICSE examination question based on "Sound":
(i) State the fundamental law or rule governing "Pitch, Loudness & Quality of Sound". [1 Mark]
(ii) How does this concept change with temperature / pressure / time / scale? [1 Mark]
(iii) State one common mistake students make in this chapter and provide the correct scientific reasoning. [2 Marks]

Step-by-Step Marking Breakdown

Part (i): Statement of the Law

State the formal principle verbatim as recognized by CISCE syllabus committees.

1 Mark

Part (ii): Dependency Analysis

Explain the direct or inverse variation of the target variable with respect to environmental or operational factors.

1 Mark

Part (iii): Error Analysis & Correct Resolution

Identify the frequent pitfall: Students often confuse Pitch determined by frequency with related quantities. The correct understanding requires strict application of Pitch, Loudness & Quality of Sound.

2 Marks

Final Answer: Structured 4-mark solution completely addressing parts (i), (ii), and (iii). (Units: Multi-part breakdown)

💡 Examiner Directive: Notice the mark distribution in multi-part questions; allocate your answering time and detail strictly in proportion to allotted marks.

Generated Practice Set 5 - Higher Order Thinking (HOTS) (4 Marks) Difficulty: Hard

4 Marks Total

A critical scenario-based problem in "Sound": An experiment is performed under non-ideal conditions involving "Pitch, Loudness & Quality of Sound" and "Pitch, Loudness & Quality of Sound".
(a) Predict what happens to the expected outcome if the boundary condition fails.
(b) Give complete scientific justification.
(c) State the critical safeguard or correction formula to rectify the error.

Step-by-Step Marking Breakdown

Part (a): Prediction of Anomalous Outcome

Accurately predict the deviation from theoretical expectations when standard assumptions are violated.

1 Mark

Part (b): Scientific Justification

Provide a rigorous scientific explanation using first principles and mandatory keywords: Pitch determined by frequency, Loudness determined by amplitude squared, Quality determined by wave-form, Audible range 20 Hz to 20,000 Hz.

2 Marks

Part (c): Correction Protocol & Mathematical Remedy

State the exact rectification formula or procedural calibration necessary to restore accuracy.

1 Mark

Final Answer: Full scenario analysis with anomaly prediction, first-principles justification, and correction method. (Units: HOTS Analytical Reasoning)

💡 Examiner Directive: HOTS questions in ICSE evaluate depth of conceptual understanding. Avoid superficial guessing; reason backward from core laws.

🔑 Mandatory ICSE Examiner Technical Keywords Required in Solutions

Required for Step-Marking Credit

CISCE evaluators check for the explicit usage of mandatory technical terminology when scoring reasoning questions and step derivations. The table below outlines each key term, its technical description, the examiner marking directive, and the exact model answer phrasing expected in ICSE board examination solutions.

Mandatory Keyword #1 Core Definition Chapter Concept: Pitch, Loudness & Quality of Sound

1 Mark (Objective / Reasoning key point)

"Pitch determined by frequency"

📘 Technical Definition & Detailed Description:

In ICSE Class 8 Physics (Sound), "Pitch determined by frequency" represents an essential governing parameter under the CISCE syllabus. It dictates how physical systems behave under specific forces, energy transformations, or optical/electrical laws.

⚠️ CISCE Examiner Directive & Marking Rubric:

CISCE examiners expect precise scientific articulation of "Pitch determined by frequency". Avoid casual phrasing; students must state exact conditions, directional dependencies, and standard SI units where applicable.

📝 Model Answer Application (Exact Phrasing for Board Solutions):

"In responses regarding Pitch, Loudness & Quality of Sound, state clearly: "Pitch determined by frequency" must be satisfied for valid physical deductions."

Mandatory Keyword #2 Core Definition Chapter Concept: Pitch, Loudness & Quality of Sound

1 Mark (Objective / Reasoning key point)

"Loudness determined by amplitude squared"

📘 Technical Definition & Detailed Description:

In ICSE Class 8 Physics (Sound), "Loudness determined by amplitude squared" represents an essential governing parameter under the CISCE syllabus. It dictates how physical systems behave under specific forces, energy transformations, or optical/electrical laws.

⚠️ CISCE Examiner Directive & Marking Rubric:

CISCE examiners expect precise scientific articulation of "Loudness determined by amplitude squared". Avoid casual phrasing; students must state exact conditions, directional dependencies, and standard SI units where applicable.

📝 Model Answer Application (Exact Phrasing for Board Solutions):

"In responses regarding Pitch, Loudness & Quality of Sound, state clearly: "Loudness determined by amplitude squared" must be satisfied for valid physical deductions."

Mandatory Keyword #3 Core Definition Chapter Concept: Pitch, Loudness & Quality of Sound

1 Mark (Objective / Reasoning key point)

"Quality determined by wave-form"

📘 Technical Definition & Detailed Description:

In ICSE Class 8 Physics (Sound), "Quality determined by wave-form" represents an essential governing parameter under the CISCE syllabus. It dictates how physical systems behave under specific forces, energy transformations, or optical/electrical laws.

⚠️ CISCE Examiner Directive & Marking Rubric:

CISCE examiners expect precise scientific articulation of "Quality determined by wave-form". Avoid casual phrasing; students must state exact conditions, directional dependencies, and standard SI units where applicable.

📝 Model Answer Application (Exact Phrasing for Board Solutions):

"In responses regarding Pitch, Loudness & Quality of Sound, state clearly: "Quality determined by wave-form" must be satisfied for valid physical deductions."

Mandatory Keyword #4 Core Definition Chapter Concept: Pitch, Loudness & Quality of Sound

1 Mark (Objective / Reasoning key point)

"Audible range 20 Hz to 20,000 Hz"

📘 Technical Definition & Detailed Description:

In ICSE Class 8 Physics (Sound), "Audible range 20 Hz to 20,000 Hz" represents an essential governing parameter under the CISCE syllabus. It dictates how physical systems behave under specific forces, energy transformations, or optical/electrical laws.

⚠️ CISCE Examiner Directive & Marking Rubric:

CISCE examiners expect precise scientific articulation of "Audible range 20 Hz to 20,000 Hz". Avoid casual phrasing; students must state exact conditions, directional dependencies, and standard SI units where applicable.

📝 Model Answer Application (Exact Phrasing for Board Solutions):

"In responses regarding Pitch, Loudness & Quality of Sound, state clearly: "Audible range 20 Hz to 20,000 Hz" must be satisfied for valid physical deductions."

⚖️ CISCE Evaluation Directives for Physics

Step-Mark Allocation: Every sub-step, formula statement, and intermediate substitution carries independent marks. Writing final answers without formula yields zero in Section B numericals.

Mandatory SI Units: In ICSE Science and Mathematics, omitting SI units or writing incorrect unit exponents causes automatic 1/2 mark deduction per problem.

Examiner Technical Vocabulary: CISCE evaluators look for exact prescribed terms in definitions and reasoning questions. General paraphrasing often loses full credit.

Sound — Solved Textbook & 5 Practice Sets

📘 Prescribed Textbook Solved Exercise (Selina Concise Physics (Class 8))

🎯 5 Generated Practice Exercises with Step-Marking

🔑 Mandatory ICSE Examiner Technical Keywords Required in Solutions

"Pitch determined by frequency"

"Loudness determined by amplitude squared"

"Quality determined by wave-form"

"Audible range 20 Hz to 20,000 Hz"

⚖️ CISCE Evaluation Directives for Physics

📚 Other Class 8 Physics Solved Exercises

Solve Exercises Interactively in the App