The answer is (4), (3) is merely a change in composition, thus not chemical but physical.
Answer: (4).
Answer:
Group 18th
Explanation:
The group 18th of periodic table which is composed of Noble gases mainly was missing from the Mendeleev's periodic table. The reason for this is that Noble gases are least reactive, therefore, it was difficult to predict such elements which do not react with other elements.
Answer:
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Explanation:
A mixture is said to be homogeneous if its composition is uniform throughout the mixture. They are referred to as solutions. On the other hand, heterogeneous mixture does not have uniform composition. The substances present in the mixture have visible difference or phases.
Sea water is composed of salt, sand and water. Here, salt and water form homogeneous mixture but due to the presence of sand, the mixture is heterogeneous. Salt dissolves in water and the solution has uniform composition but sand does not dissolve in water, even after vigorous mixing, after some time it settles at the bottom resulting formation of layers. Thus, sea water containing salt, water and sand is a heterogeneous mixture.
Answer: Sustainable living
Explanation: It is a lifestyle by which an individual uses natural resources only as much as is necessary, which means in limited quantities, and thus reduces the general enormous exploitation of these resources. In this way, the needs of the individual are met and resources are put to use for generations to come. It also refers to personal resources as well as Earth resources in general.
It is obvious from today's point of view that if food was produced only as much as needed, it would mean not throwing away food, everyone, both those who could otherwise afford food and those who are now starving, would be fed up.
With the reduction of production not only of food but also of other necessities, that is, with production to meet the needs and not beyond, there would be less pollution and less emission of harmful hags and greenhouse effect.