A compound<span> is a </span>pure substance<span> composed of two or more different atoms chemically bonded to one another. A </span>compound<span> can be destroyed by chemical means. It might be broken down into simpler </span>compounds<span>, into its elements or a combination of the two.</span>
A. True
They are formed behind an obstacle when the wind blows the sand up to it.
Answer:
Carbon or the symbol C has a mass percentage of 42.880% while Oxygen or symbol O has a mass percentage of 57.120%
Answer: The reactivity of group 7 decreases as we move down the group because:
Explanation:
The elements of group 7 that is fluorine to iodine. The halogens are non metals and they react with metals to gain electrons. The metals loose electrons and the non metal gains it.
As we move down the group the atomic radius gets bigger( more electron and more proton) and as a result the outer shells move further away from the nucleus.
There is more distance between the negatively charged electrons and positively charged nucleus.
Therefore the force of attraction between the shells and nucleus is lesser or weaker.
This makes attracting an extra electron from metals very difficult which results in weaker reaction.
Consequently, the reactivity decreases as we move down the group 7
The first statement (Matter is neither created nor destroyed) is correct.
The second statement would violate the law of conservation of mass (I will refer to this as LCM), as it would mean matter can "flow" into the universe, but not out, meaning the total matter will never be less than it was before.
The third statement violates LCM because it means matter is created during a reaction, which is not true.
The last statement violates LCM because it means matter is lost during a reaction, which is not true.
