Advertisements
Advertisements
Question
A thick coating of a paste of Plaster of Paris (POP) is applied over the bandage on a fractured bone. It becomes hard on drying to keep the fractured bone immobilised. Can the change in POP be reversed?
Advertisements
Solution
When water is added to plaster of Paris (POP), it changes to another substance, and on drying it hardens. Once the POP has hardened, its shape cannot be changed. Therefore, the change in POP cannot be reversed.
RELATED QUESTIONS
How is a strong electrolyte different from a weak electrolyte?
Give reason for the following:
Silver nitrate solution is kept in coloured bottles.
Give reason for the following:
Colourless concentrated sulphuric acid in a test tube changes to blue on adding a small piece of copper to it.
Give one example electrochemical reaction.
Name the gases which turn moist red litmus blue.
Write your observation and a balanced equation in the case of the following substances being heated.
Ammonium chloride
On heating which of the following substances i.e. copper carbonate, zinc carbonate, washing soda, copper sulphate, zinc nitrate, copper nitrate, lead nitrate, ammonium chloride and ammonium dichromate – relate to the reaction given below.
A white solid which evolves two colourless gases which on cooling combine and condense on the cooler parts of the test tube.
Give balanced equation for the following conversion affected by heat alone on the substance:
Zinc nitrate to nitrogen dioxide
Explain the Silver nitrate solution is kept in coloured reagent bottles in the laboratory.
Rusting of iron is ______.
