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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
Dry HCl gas does not change the colour of dry litmus paper because: (A) HCl is a weak acid (B) HCl does not ionise in the absence of water (C) Litmus reacts only with bases (D) HCl gas has no hydrogen in it
  1. A HCl is a weak acid
  2. B HCl does not ionise in the absence of water
  3. C Litmus reacts only with bases
  4. D HCl gas has no hydrogen in it
Generated by claude-sonnet-4-6 · 2026-06-26 01:03 · grounding rag
Model Answer

(B) HCl does not ionise in the absence of water

Explanation

The textbook (Activity 2.9) states that H⁺ ions are produced by HCl only in the presence of water. Dry HCl gas has no water to enable ionisation, so no H⁺(aq) ions are formed, and litmus (which responds to ions) does not change colour. HCl is actually a strong acid, so option A is factually wrong.

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