Science
With the help of an activity, explain the conditions under which iron articles get rusted.
Answer
To show the conditions under which iron gets rusted, take three test tubes containing iron nails and set them up as follows:
- Test tube 1: Contains distilled water — both air (oxygen) and water are present.
- Test tube 2: Contains boiled water with a layer of oil — only water is present, no air.
- Test tube 3: Contains anhydrous calcium chloride — only dry air is present, no water.
After a few days, only the iron nails in test tube 1 get rusted, showing that both air (oxygen) and moisture (water) are necessary for rusting. Thus, rusting of iron occurs only when iron, oxygen, and water are all present.
Related Questions
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(a) "Displacement reactions also play a key role in extracting metals in the middle of the reactivity series." Justify this statement with two examples.
(b) Why can metals high up in the reactivity series not be obtained by reduction of their oxides by carbon ?
(a) Name two metals which react violently with cold water. List any three observations which a student notes when these metal are dropped in a beaker containing water.
(b) Write a test to identify the gas evolved (if any) during the reaction of these metals with water.
Plants have neither a nervous system nor muscles, even then they respond to stimuli. For example, the leaves of chhui-mui (touch-me-not) plant when touched begin to fold up and droop.
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(b) What enables the plant cells to bring out the observable response ?
(c) Differentiate the movement mentioned above from the movement of tendrils in a pea plant.