Class 10Subject Code: 086Year: 202639 Questions Available

CBSE Class 10 Science 2026 — QuizCluster Solutions

Comprehensive question-by-question independently authored solutions for CBSE Class 10 Science Board Examination (2026). Questions are referenced directly to the official CBSE Question Paper.

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Official Source & AttributionSource of question paper: Central Board of Secondary Education (CBSE)

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Q1 of 39

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Decomposition of Lead Nitrate on Heating

Section A•1 Marks•Chapter: Chemical Reactions and Equations

Easy

Question 1 — Problem Statement (Synopsis)

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When solid lead nitrate Pb(NO₃)₂ is heated strongly in a dry test tube, the brown fumes evolved and the residue left behind are respectively:

See Question 1 in official CBSE Class 10 Science Question Paper (2026)

QuizCluster Step-by-Step Solution

Step 1: Balanced chemical thermal decomposition equation

2Pb(NO₃)₂(s) —[Heat]→ 2PbO(s) [Yellow residue] + 4NO₂(g) [Brown fumes] + O₂(g) [Colourless gas].

Step 2: Identify observed products

The pungent brown fumes are Nitrogen Dioxide (NO₂) gas, and the solid residue left in the test tube is yellow Lead(II) Oxide (PbO).

Final Answer

Brown fumes: Nitrogen Dioxide (NO₂) | Residue: Yellow Lead(II) Oxide (PbO)

Key Formulas & Mathematical Laws

2Pb(NO₃)₂(s) → 2PbO(s) + 4NO₂(g) + O₂(g)

Important Core Concept

Thermal decomposition is an endothermic reaction breaking down a single reactant into three distinct products.

Common Student Pitfall

Confusing brown fumes of NO₂ with N₂O or NO.

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Question 1 of 39

Source of question paper: Central Board of Secondary Education (CBSE). QuizCluster provides independently prepared educational solutions and explanations. QuizCluster is an independent educational platform and is not affiliated with or endorsed by CBSE. Question papers are accessed through links to official CBSE resources and are not hosted by QuizCluster.