Chemistry Chapter 6 Board Weightage: 12 Marks in Class 9 Exams

Study of the First Element - Hydrogen

Prescribed Textbook: Selina Concise Chemistry (Class 9) - Chapter 6

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📖 Syllabus Scope & Overview

Unique dual position of hydrogen (resemblance with alkali metals and halogens), laboratory preparation of hydrogen from granulated zinc and dilute acid, Bosch process, and oxidation-reduction in terms of electron transfer.

💡 Core Concepts & Curriculum Outline

Master the fundamental theoretical framework and syllabus scope approved by CISCE.

Laboratory Preparation of Hydrogen

Zn + 2HCl(dil.) -> ZnCl2 + H2↑. Granulated zinc is preferred because it contains trace copper impurity which acts as a catalyst. Collected by downward displacement of water because it is lighter than air and almost insoluble in water.

🔑 Mandatory ICSE Examiner Technical Keywords with Detailed Description

Official CISCE Evaluation Benchmark

According to CISCE board marking schemes, evaluators allocate marks based on the explicit presence of mandatory technical keywords. General or colloquial explanations fail to secure full marks. The table below details every required technical term, its scientific/academic description, the evaluator directive, and its exact model answer usage.

Mandatory Keyword #1 Core Definition Chapter Concept: Laboratory Preparation of Hydrogen

1 Mark in Chemical Observation / Balanced Equation

"Granulated zinc with dil. HCl"

📘 Technical Definition & Detailed Description:

In ICSE Class 9 Chemistry (Study of the First Element - Hydrogen), "Granulated zinc with dil. HCl" denotes a critical reaction condition, bonding mechanism, stoichiometric rule, or analytical observation required by CISCE.

⚠️ CISCE Examiner Directive & Marking Rubric:

Examiners award marks specifically when "Granulated zinc with dil. HCl" is included alongside balanced chemical equations, observable color changes, or state symbols (s, l, g, aq).

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

"During the reaction in Laboratory Preparation of Hydrogen, ensure "Granulated zinc with dil. HCl" is explicitly stated in the balanced explanation."

Mandatory Keyword #2 Core Definition Chapter Concept: Laboratory Preparation of Hydrogen

1 Mark in Chemical Observation / Balanced Equation

"Downward displacement of water"

📘 Technical Definition & Detailed Description:

In ICSE Class 9 Chemistry (Study of the First Element - Hydrogen), "Downward displacement of water" denotes a critical reaction condition, bonding mechanism, stoichiometric rule, or analytical observation required by CISCE.

⚠️ CISCE Examiner Directive & Marking Rubric:

Examiners award marks specifically when "Downward displacement of water" is included alongside balanced chemical equations, observable color changes, or state symbols (s, l, g, aq).

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

"During the reaction in Laboratory Preparation of Hydrogen, ensure "Downward displacement of water" is explicitly stated in the balanced explanation."

Mandatory Keyword #3 Core Definition Chapter Concept: Laboratory Preparation of Hydrogen

1 Mark in Chemical Observation / Balanced Equation

"Insoluble in water"

📘 Technical Definition & Detailed Description:

In ICSE Class 9 Chemistry (Study of the First Element - Hydrogen), "Insoluble in water" denotes a critical reaction condition, bonding mechanism, stoichiometric rule, or analytical observation required by CISCE.

⚠️ CISCE Examiner Directive & Marking Rubric:

Examiners award marks specifically when "Insoluble in water" is included alongside balanced chemical equations, observable color changes, or state symbols (s, l, g, aq).

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

"During the reaction in Laboratory Preparation of Hydrogen, ensure "Insoluble in water" is explicitly stated in the balanced explanation."

Mandatory Keyword #4 Core Definition Chapter Concept: Laboratory Preparation of Hydrogen

1 Mark in Chemical Observation / Balanced Equation

"Catalytic trace copper"

📘 Technical Definition & Detailed Description:

In ICSE Class 9 Chemistry (Study of the First Element - Hydrogen), "Catalytic trace copper" denotes a critical reaction condition, bonding mechanism, stoichiometric rule, or analytical observation required by CISCE.

⚠️ CISCE Examiner Directive & Marking Rubric:

Examiners award marks specifically when "Catalytic trace copper" is included alongside balanced chemical equations, observable color changes, or state symbols (s, l, g, aq).

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

"During the reaction in Laboratory Preparation of Hydrogen, ensure "Catalytic trace copper" is explicitly stated in the balanced explanation."

📝 Solved Textbook & 5 Generated Practice Exercises

Open Dedicated Exercise Page (class9_chemistry_solved_exercise_study_of_the_first_element_hydrogen.html) →

Complete step-by-step evaluator solutions for textbook problems and 5 generated practice sets adhering to CISCE marking schemes.

📘 Textbook Problem: Textbook Exercise 6 - Section Review Q.3

Selina Concise Chemistry (Class 9) - Chapter 6 - Review Exercise 6 3 Marks Total

In the study of Study of the First Element - Hydrogen: (i) Give a balanced chemical equation or reaction mechanism illustrating Laboratory Preparation of Hydrogen. (ii) State two visible observations when this reaction occurs in the laboratory.

Step-by-Step Marking Breakdown

Step 1: Write Balanced Chemical Equation: Write the complete chemical equation with correct molecular formulas, balancing coefficients, and state symbols (s, l, g, aq). 1 Mark

Step 2: Detail First Characteristic Observation: State the primary sensory observation (e.g. color change, gas evolution with specific smell/test, or precipitate formation). Do not simply state the chemical name of the product formed. 1 Mark

Step 3: Detail Second Observation and Chemical Inference: State the second distinguishing property or test verifying the chemical reaction has reached completion. 1 Mark

Final Answer: Balanced equation and distinct physical observations confirmed (Units: State symbols (s, l, g, aq))

💡 Examiner Tip: In ICSE Chemistry, an "observation" must describe what is physically seen, smelled, or heard, NOT just naming the compound formed.

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

ICSE Class 9 Exam Blueprint - Chapter 6 2 Marks Total

Define "Laboratory Preparation of Hydrogen" in the context of ICSE Class 9 Chemistry. State its primary characteristic or SI unit/standard symbol.

Step-by-Step Marking Breakdown

Step 1: Precise Technical Definition: Zn + 2HCl(dil.) -> ZnCl2 + H2↑. Granulated zinc is preferred because it contains trace copper impurity which acts as a catalyst. Collected by downward displacement of water because... 1 Mark

Step 2: Mandatory Technical Criteria: Ensure the definition contains mandatory keywords: Granulated zinc with dil. HCl, Downward displacement of water, Insoluble in water. 1 Mark

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

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

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

ICSE Question Bank & Specimen Framework - Chemistry 3 Marks Total

Explain the procedural method or practical demonstration used to verify "Laboratory Preparation of Hydrogen". 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 Laboratory Preparation of Hydrogen. 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 Laboratory Preparation of Hydrogen (Units: Procedural steps)

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

🎯 Generated Set: Generated Practice Set 3 - Comparative Analysis (3 Marks)

ICSE Exemplar Practice Paper - Chemistry 3 Marks Total

Differentiate between "Laboratory Preparation of Hydrogen" and "Laboratory Preparation of Hydrogen" 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: Laboratory Preparation of Hydrogen focuses on Granulated zinc with dil. HCl, whereas Laboratory Preparation of Hydrogen emphasizes Granulated zinc with dil. HCl. 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 Tip: Always construct a comparative answer in a two-column table with an explicit "Point of Difference" header column.

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

ICSE Board Marking Blueprint - Class 9 4 Marks Total

A comprehensive ICSE examination question based on "Study of the First Element - Hydrogen":
(i) State the fundamental law or rule governing "Laboratory Preparation of Hydrogen". [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 Granulated zinc with dil. HCl with related quantities. The correct understanding requires strict application of Laboratory Preparation of Hydrogen. 2 Marks

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

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

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

ICSE High-Achiever Challenge Series - Class 9 4 Marks Total

A critical scenario-based problem in "Study of the First Element - Hydrogen": An experiment is performed under non-ideal conditions involving "Laboratory Preparation of Hydrogen" and "Laboratory Preparation of Hydrogen".
(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: Granulated zinc with dil. HCl, Downward displacement of water, Insoluble in water, Catalytic trace copper. 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 Tip: HOTS questions in ICSE evaluate depth of conceptual understanding. Avoid superficial guessing; reason backward from core laws.

📚 Other Class 9 Chemistry Chapters

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