Question

1. One teaspoon of salt is dissolved in a glass of water. How can you obtain salt from this salt solution?
Why is dissolving of salt in water a reversible and physical change?
2. In some carts, a metal rim is fixed over the wooden wheels to prevent the wear and tear of the wooden
wheels. To prevent the metal rim from falling off, it is made in a slightly smaller size than the wooden
wheel. Can you suggest how the smaller-sized metal rim is placed over the wooden wheel? ​

Answer 1

Answer:

1. Dissolving a solid in liquid, such as table salt in water, is a physical change because only the state of the matter has changed. Physical changes can often be reversed. . It has not combined with the water to cause a chemical reaction.  We can obtain salt from its solution by heating or letting the water evaporate. Dissolving a solid in liquid, such as table salt in water, is a physical change because only the state of the matter has changed. Physical changes can often be reversed. Allowing the water to evaporate will return the salt to a solid state. It has not combined with the water to cause a chemical reaction.

2. Metal Rim of wooden wheel is made smaller in size because, when it is heated it expands  and becomes bigger than the Wooden Wheel. when this expanded Metal Rim is put over the Wooden Wheel and Cold Water is poured over it, The Metal Rim has a Tight Fitting.