Chemical and Physical Changes Quiz

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Questions and Answers

What occurs when milk is left at room temperature during summers?

It remains unchanged
It undergoes a chemical change due to the action of microorganisms (correct)
It evaporates completely
It curdles due to the action of enzymes

What happens when grapes get fermented?

They become sour
They remain unchanged
They undergo a chemical change due to the action of microorganisms (correct)
They become juicier

What do we observe when food is cooked?

The food loses water content
The food becomes colder
A chemical change occurs due to the application of heat (correct)
No change occurs

What do we come to know when a chemical reaction has taken place?

A change in the nature and identity of the initial substance occurs (B) Signup and view all the answers

What is meant by a chemical reaction?

A process where one or more substances are converted into different substances with different properties (D) Signup and view all the answers

What is the purpose of burning a magnesium ribbon in the activity described in the text?

The purpose is to observe the chemical reaction that occurs when magnesium burns in air to form magnesium oxide. Signup and view all the answers

What precautionary measures are recommended for the activity involving burning a magnesium ribbon?

The activity requires the teacher's assistance and students are advised to wear suitable eyeglasses. Additionally, the magnesium ribbon should be burned away from the eyes. Signup and view all the answers

What is the primary change observed when food is cooked?

The primary change observed when food is cooked is a chemical change, as the nature and identity of the initial substances have somewhat changed. Signup and view all the answers

How can we determine if a chemical reaction has taken place?

A chemical reaction is indicated by the occurrence of a chemical change in which the nature and identity of the initial substances have changed. Signup and view all the answers

When does a chemical reaction occur?

A chemical reaction occurs when a chemical change takes place, resulting in a change in the nature and identity of the initial substances. Signup and view all the answers