Ravi wants to experiment with sugar cubes. which of the following causes a sugar cube to only change physically not chemically A)burning the sugar cube with a match. B) crushing the sugar cube and dissolving it in water C) Treating the sugar cube with sulphuric acid D) chewing the sugar cube and digesting it
Answers
Answer:
(B) crushing the sugar cube and dissolving it in water
Explanation:
Physical changes are those changes in which only the physical properties of the substances are changed and no new substance is formed. The chemical composition of the substances remains the same.
Chemical changes are those changes in which chemical properties of the substances are also changed along with physical properties and one or more new substances are formed.
Let's see why option (B) is the answer of this question.
(A) burning the sugar cube ❎
When we burn a sugar cube, the chemical composition of sugar changes and sugar reacts with oxygen to form new substances including smoke. Hence, it is a chemical change. Remember, the burning of any substance is a chemical change.
(B) crushing the sugar cube and dissolving it in water ✅
When we crush a sugar cube, we only change its physical appearance. When we dissolve it in water, its particles get into the spaces between the water particles. No new substance is formed and there is no chemical reaction happening. Hence, it is a physical change and the correct answer of this question.
(C) treating the sugar cube with sulphuric acid ❎
When we treat sugar cube with sulphuric acid, it reacts with sulphuric acid and forms carbon snake, a black solid-liquid mixture. So, here a chemical reaction is happening. Hence, it is a chemical change. Remember, whenever there is a chemical reaction happening, the change is a chemical change.
(D) chewing the sugar cube and digesting it ❎
When we chew a sugar cube (or any food), saliva and other enzymes are secreted which break it down into simpler substance. Further, when it is digested, many liquids are secreted which digest, i.e., break it into very simple forms. So, after digestion, a new substance is formed. So, this is also a chemical change.