Which answer choices best indicate that a substance has experienced a chemical change?
• when a new substance is formed
• when the substance changes forms
• when the substance changes color or odor
• when energy (heat or light) is absorbed or released
• when a gas is produced or bubbles are seen
• when the substance becomes reactive or starts decomposing
The answer choices that best indicate that a substance has experienced a chemical change are:
1. when a new substance is formed: This indicates a chemical change because the original substance has transformed into a different substance with new properties.
2. when the substance changes forms: This alone does not necessarily indicate a chemical change. Changing forms can refer to physical changes, such as changing from a solid to a liquid, without any change in the chemical composition of the substance.
The answer choices that best indicate that a substance has experienced a chemical change are:
1. When a new substance is formed.
2. When the substance changes forms.
To determine if a substance has undergone a chemical change, you need to look for evidence of a chemical reaction. Chemical reactions occur when bonds between atoms are broken or formed, resulting in a new substance or substances being produced.
The first answer choice, "when a new substance is formed," is a clear indicator of a chemical change. If the properties and composition of the substance change significantly to produce a substance with different properties, it suggests a chemical reaction has taken place.
The second answer choice, "when the substance changes forms," is also an indicator of a chemical change. Chemical reactions often involve the transformation of substances from one state or form to another. For example, if a solid substance is heated and turns into a gas, or if a liquid substance changes color or releases gas bubbles, it may indicate a chemical change.
By considering these answer choices, you can identify indications of a chemical change in a substance.