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प्रश्न
A chemical reaction is generally accompanied by certain external indications or characteristics. These include – change of – (a) colour (b) state (c) smell (d) evolution of gas (e) formation of precipitate (f) evolution or absorption of heat. With reference to change of colour – state the change in colour seen when the following are heated – mercury [II] oxide.
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उत्तर
Change of colour — In certain chemical reactions a change of colour is seen to be observed. Heat on substances to observe change in colour of reactants and products.
Heat on:
Mercury [II] oxide 2HgO → 2Hg + O2 [g]
Colour change:
Mercury [II] oxide [HgO] – Red – to Mercury [Hg] – Silvery
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संबंधित प्रश्न
Balance the gievn equation:
NaOH + H2SO4 
Na2SO4 + H2O
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(a) law of conservation of momentum
(b) law of conservation of mass
(c) law of conservation of motion
(d) law of conservation of magnetism
Write symbolic representation for the following word equation and balance them :
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Write symbolic representation for the following word equation and balance them :
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Why should an equation be balanced? Explain with the help of a simple equation.
Write the balanced chemical equation of the following reaction.
barium chloride + sulphuric acid → barium sulphate + hydrochloric acid
Write the balanced chemical equation of the following reaction.
sulphur + nitric acid→ sulphuric acid + nitrogen dioxide + water.
With reference to a chemical equation state which of the statements 1 to 5 pertain to A or B.
A: Information provided by a chemical equation.
B: Limitations of a chemical equation.
- The nature of the individual elements.
- The speed of the reaction.
- The state of matter in which the substance is present.
- The completion of the reaction.
- The direction of the reaction.
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Complete the following blank in the equation as indicated.
\[\ce{CaH2_{(s)} + 2H2O_{( aq)}-> Ca(OH)2_{(s)} + 2H2_{(g)}}\]
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