PUMPA - SMART LEARNING

எங்கள் ஆசிரியர்களுடன் 1-ஆன்-1 ஆலோசனை நேரத்தைப் பெறுங்கள். டாப்பர் ஆவதற்கு நாங்கள் பயிற்சி அளிப்போம்

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1. A substance X, which is an oxide of a group 2 element, is used intensively in the cement industry. This element is present in bones also. On treatment with water it forms a solution which turns red litmus blue. Identify X and also write the chemical reactions involved.
 
The given substance X is . Calcium oxide is used intensively in the cement industry. The element present in bones also is calcium. Calcium oxide mixed with water forms a solution of (Ca(OH)_2), which is an alkali. As a result, it turns red litmus blue.
 
The chemcal equation of the above finding is 2CaO(s) + H_2​O(l) → Ca(OH)_2​(aq).
 
2. A silver article generally turns black when kept in the open for a few days. The article when rubbed with toothpaste again starts shining.Why do silver articles turn black when kept in the open for a few days? Name the phenomenon involved.
  
The silver article turns black when kept in the air because the silver article reacts with sulphur compounds such as (H_2​S) present in the air.

Ag + H_2​SAg_2​S + H_2

The phenomenon is called corrosion. It is called .