True
Explanation:
The physical properties and the chemical reactivity of halogens are best investigated in several different compounds. Compounds of a substance gives us good knowledge about how they behave and exists in nature.
- Halogens are very reactive group of elements.
- Due to their high electronegativity, they are the most reactive on the periodic table.
- They tend to find one electron to complete their octet by all means.
- They favor reactions where they have easy access to electrons.
- When atoms combines, they have different chemical properties.
- When the molecules combine to form intermolecular bonds, it tells on their physical properties.
- The compounds of halogens is a very good way to investigate their chemical reactivity and physical properties.
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Reactivity brainly.com/question/6496202
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Radiation - The other two ways are conduction and convection, both of which need matter to transfer energy.
Answer:
a solution color becoming less intense due to dilution- is not an evidence of a chemical reaction
bubbles (gas formation) - evidence of a chemical reaction
explosion or fire - evidence of a chemical reaction
changes in color- evidence of a chemical reaction
precipitation- evidence of a chemical reaction
changes in temperature - evidence of a chemical reaction
a solid liquifying - is not an evidence of a chemical reaction
solution colors mixing - is not an evidence of a chemical reaction
Explanation:
A chemical change is not easily reversible and yields new substances. It is often accompanied by a loss or gain of heat.
In the answer section, i have shown some evidences that lead us to conclude that a chemical reaction has taken place. The occurrence of a chemical change often goes with the formation of new substances as earlier stated and any of these signs may accompany the process.
For instance, when a metal is dropped in dilute acid solution, bubble of hydrogen gas indicates that a chemical reaction has taken place.