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Some Basic Concepts of Chemistry — Chemistry STD 11 Science — Question

Rajasthan BoardEnglish MediumSTD 11 ScienceChemistrySome Basic Concepts of Chemistry3 Marks
Question
  1. Classify the following substances into elements, compounds and mixtures.
  1. 2-Carat gold.
  2. Sucrose.
  3. Diamond.
  4. Sodium chloride.
  1. How many significant figures are there in each of the following numbers?
  1. 12
  2. 2.084
  1. What do you understand by the rounding off a number?
  2. Write balanced chemical equations for the following:

Na2CO(aq) + NO(g) + NO3(g) → NaNO2(aq) + CO2(g)

✓

Answer

  1.  
    1. Mixture (Homogeneous).
    2. Compound.
    3. Element.
    4. Compound.
  2.  
    1. 2
    2. 4
  3. Rounding off a number means that figures which are not significant for the purpose at hand are dropped.
  4. Na2CO3(aq) + NO(g) + N03(g) → 2NaNO2(aq) + C02(g)

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