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Science (086) — AI-generated practice question

AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.

Q1. [1] medium exam-ready
Assertion (A): Plaster of Paris should always be stored in a moisture-proof container. Reason (R): Plaster of Paris reacts with water to form gypsum (CaSO₄.2H₂O), losing its ability to set.
  1. A Both A and R are true and R is the correct explanation of A.
  2. B Both A and R are true but R is not the correct explanation of A.
  3. C A is true but R is false.
  4. D A is false but R is true.
Generated by claude-sonnet-4-6 · 2026-06-26 01:03 · grounding rag
Model Answer

Option A — Both A and R are true and R is the correct explanation of A.

Plaster of Paris (CaSO₄·½H₂O) reacts with water to form gypsum (CaSO₄·2H₂O), losing its setting property, so moisture-proof storage is essential.

Explanation

The Assertion is correct — moisture ruins PoP by triggering premature setting. The Reason correctly explains why: the reaction with water converts PoP back to gypsum, so it can no longer set when needed. Since R directly and correctly explains A, option A is the right choice. Note: the source passages provided do not cover PoP, but this is standard Class 10 Science (Chapter 2 — Acids, Bases and Salts) factual knowledge expected in the exam.

Previous-year CBSE Grade 10 board exam questions, organised by subject and chapter, each with a model answer — free to read and print.