Give one example each of a chemical reaction characterised by: evolution of gas, change in colour, formation of a precipitate, change in temperature and change in state
(class 10 CBSE SAMPLE PAPER 2017-18 SCIENCE)give one example of chemical reaction
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1. Change in colour :
The reaction between lead nitrate solution and poassium iodide solution.
Chemical equation as follow :
Pb ( NO₃ )₂ + 2 KI ⇒ PbI₂ + 2 KNO₃
In above reaction colour change from colourless to yellow.
2. Change in temperature :
The reaction between dil. sulphuric acid on zinc.
Chemically :
Zn + H₂SO₄ ⇒ ZnSO₄ + H₂
Heat evolved in the above reaction.
3. Formation of precipitation :
The reaction between barium chloride on sodium sulphate.
Chemically :
BaCl₂ + Na₂SO₄ ⇒ BaSO₄ + 2 NaCl
In the above reaction white ppt. of BaSO₄ will form.
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