Because gravity has been known to define as a force of attraction between things that have mass.
The complete statement is "chemical properties can be observed only when the substance in a sample of matter are changing into different substance".
It states a key concept in chemistry.
A chemical property is the ability of a substance, element or compound, to <em>transform</em> into other substances either <em>by decomposing or by combining</em> with one or more substances.
This transformation is defined as chemical reaction.
During chemical reactions some chemical bonds are broken and others are formed leading to the formation of one or more different substances called products.
Some examples of chemical properties are: reactivity with oxygen, reactivity with water, acidity, basicity, oxidation, reduction. The only way to tell if a substance has certain chemical property is by letting it react and so observe the change of the original substance into one or more different substances.
Answer:
Sound needs a material medium for their propagation like solid, liquid or gas to travel because the molecules of solid, liquid and gases carry sound waves from one point to another. Sound cannot progress through the vacuum because the vacuum has no molecules which can vibrate and carry the sound waves.
Heres your great lovley answer that you need
<em>Ten games</em> will be played.
The first team can be any one of 5 . For each of those, the opponent can be any one of the other 4 .
Number of ways to pair them up = (5 x 4) = 20 ways .
<em>BUT</em> ... Whether the Reds play the Blues, or the Blues play the Reds, it's the SAME GAME. Each possible game shows up twice in the list of 20 ways. So there are really only 10 different pairs ==> <em>10 games</em> .
