Bavitaa Foundation Chemistry Quiz-4

Chlorine is commonly used to treat water because it has strong disinfectant properties. It effectively kills germs and bacteria present in the water, making it safe for consumption. This process helps to prevent the spread of waterborne diseases and ensures that the water is clean and free from harmful microorganisms.

Sugar is the only crystalline substance among the options provided. Crystalline substances have a regular, repeating pattern in their molecular structure, resulting in a well-defined shape and form. Sugar, also known as sucrose, forms crystals when it solidifies. On the other hand, coal, wax, and clay do not have a crystalline structure and do not form regular repeating patterns.

Water, petrol, and mercury are all substances that are normally in a liquid state. Water has a melting point of 0 degrees Celsius and a boiling point of 100 degrees Celsius, which means it exists as a liquid at room temperature. Petrol, or gasoline, is a liquid fuel that is commonly used in vehicles and has a low boiling point. Mercury is a heavy metal that is liquid at room temperature and commonly used in thermometers. Therefore, all of the options listed (water, petrol, and mercury) are in a liquid state normally.

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The change given in the question is an example of a chemical change. In a chemical change, the substances involved undergo a chemical reaction, resulting in the formation of new substances with different properties. This is different from a physical change, where the substances involved do not undergo a chemical reaction and only their physical properties change. Since the change given in the question involves a chemical reaction, it is classified as a chemical change.