Question

VI. GIVE REASONS FOR THE FOLLOWING:
1. White phosphorous is stored under water,
2. We should avoid standing close to a tuberculosis patient while he/she is coughing.
3. Fresh milk is boiled before consumption while processed milk is stored in packets and can be
consumed without boiling,
4. It is dangerous to handle electrical appliances with wet hands or while standing on a wet
floor.
5. Instead of taking the trouble of electroplating metals with chromium for making car parts,
taps, cycle parts, etc., why are these objects not made of chromium itself?
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Answer 1

Answer:

1. White phosphorus is stored in water because it is highly reactive with air and explodes when comes in contact of air.
2. We should avoid standing close to a tuberculosis patient while he/she is coughing because tuberculosis is a disease which is transmitted through air and the nearer we stand near the infected person , the more we have a chance of acquiring the disease.
3. Fresh milk may contain some micro-organisms which may be harmful when consumed, so it is necessary to boil the milk. Whereas packed milk can be consumed without boiling because processed milk is already pasteurized and free from pathogens.
4. Water is a very good conductor of electricity. So, while handling electrical appliances with wet hands we have a fair chance of getting an electrical shock.
5. We electroplate metal objects with chromium to prevent their damage due to oxidation. Solid chromium cannot be used for this purpose. Bulk chromium is very uncommon. Most people do not ask for bulk chromium because only a plating of a few microns serve the purpose. Solid chromium made metal objects would no longer be shiny and will be very expensive. It is expensive because most of the chromium in mines changes into chromic acid which has to be changed again to chromium making the process expensive. Hence chromium plated metal objects are mostly used