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Dil. HCl is added to… (Class 10 Science SQP 2023-24, Q21)

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ScienceCBSE Class 10 · Sample paper, session 2023-24 · 2 marks · Very short answer

CBSE Class 10 Science sample paper 2023-24: question 21

From the official CBSE sample question paper for 2023-24, section B, question 21, for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q21 · 2 marks · Very short answerChemical Reactions and Equations

Dil. HCl is added to Zn granules. How will you prove that chemical change has taken place here? Support your response with two arguments.

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2023-24.

Hints

Open one hint at a time and try again before the next.

Hint 1

List the signs that show a chemical reaction has happened.

Hint 2

What do you see and feel at the test tube when zinc reacts with the acid?

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. Reaction: . A new substance forms, so a chemical change takes place. Two observations prove this:

  2. Argument 1: Bubbles of a gas appear (evolution of gas). The gas is hydrogen, which burns with a pop sound.

    1 mark

  3. Argument 2: The test tube becomes warm, showing a change in temperature (heat is released). The zinc granules may also turn from silvery grey to dark.

    1 mark

Answer: Evolution of hydrogen gas (bubbles) and change in temperature (or change in colour of Zn)

Where the marks are

  • Evolution of gas/bubbles as evidence (1 mark)
  • Change in temperature or change in colour of zinc as second evidence (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Chemical Reactions and Equations, one at a time, marked against the answer key and marking points.Back to the full paperSample paper 2023-24: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.