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SVEN [57.7K]
3 years ago
12

How do we know that air we breathe is matter?

Chemistry
2 answers:
Viefleur [7K]3 years ago
6 0
Because all matter has density and since air has density then air is matter and plus EVERYTHING is made of matter
daser333 [38]3 years ago
5 0

Nerves inside us. They send signals to our brains.

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In a chemical formula, what is used to indicate the number of atoms of each element?
MrRa [10]
The coefficients next to the symbols of entities indicate the number of moles of a substance produced or used in the chemical reaction.
6 0
2 years ago
Arrange the following chloroarenes in increasing order of their reactivity in nucleophilic substitution to form their correspond
pantera1 [17]
The question is incomplete. Complete question is attached below
..............................................................................................................................

Correct Answer: Option C i.e. I ~ III < IV < V < II

Reason:
During a nucleophilic subsitution reaction of chloroarenes, Cl- group is replaced by an nucleophile like OH-.

Order of reactivity, during such reactions depends on the electron density on carbon atom that is attached to Cl. Lower the electron density, greater will be the reactivity.

Among the provided chloroarenes, electron density on C atom will be minimum in case of compound II, because of presence of electron withdrawing group (-NO2) at ortho and para position. Due to this, there will be large number of resonating structures. This signifies greater electron de-localization, and hence largest reactivity for nucleophilic substitution reaction.

Followed by this, compound V will show greater reactivity, due to presence of -NO2 group at para and one of the ortho position. Compound IV will have less number of resonating structures as compared to compound II and V, hence it will display poor reactivity towards nucleophilic substitution reaction.

Finally, compound 1 and III will minimum reactivity towards nucleophilic substitution reaction, because -NO2 group present at meta position (compound III) will not participate in resonance.  



6 0
3 years ago
At 25 ∘C the reaction CaCrO4(s)←→Ca2+(aq)+CrO2−4(aq) has an equilibrium constant Kc=7.1×10−4. What is the equilibrium concentrat
Nitella [24]

Answer:

2.67 × 10⁻²

Explanation:

Equation for the reaction is expressed as:

CaCrO₄(s)    ⇄      Ca₂⁺(aq)         +        CrO₂⁻⁴(aq)

Given that:

Kc=7.1×10⁻⁴

Kc= [Ca^{2+}][CrO^{2-}_4]

Kc= [x][x]

Kc= [x²]

7.1×10⁻⁴ =  [x²]

x = \sqrt{7.1*10^{-4}}

x = 0.0267

x = 2.67*10^{-2}

6 0
3 years ago
What is the formula for solid sodium metal reacts with solid iron (lll) chloride. Solid iron metal and solid sodium chloride are
sineoko [7]

Answer:

Explanation:When sodium metals reacts with iron (ll) chloride,iron metal and sodium chloride are formed. -2 Na(s)+fella(s) fev(s)+2Naci.

3 0
2 years ago
sodium chloride is made up of sodium and chlorine, but it isn't a poisonous gas and it doesn't explode in water. explain why.
jenyasd209 [6]

sodium chloride is a compound that is stable because its constituent elements namely chlorine and sodium have formed ionic bonds with each other and their outer energy shells are filled with 8 electrons. 

Sodium on its own  has 11 electrons. Two of these are in the 1st energy level, eight in the 2nd energy level and one in the 3rd energy level. This arrangement is highly unstable rendering the element sodium highly unstable and reactive. It will burst into flames immediately on exposure to air and can burn through human flesh if it comes into contact with it.

Chlorine at room temperature is a poisonous gas. It has 17 electrons in the arrangement 2:8:7 . The outermost shell has 7 electrons and so this element is fairly stable but will readily react with human lungs with fatal consequences.

So each of these two elements on their own are deadly, but when the two react together, sodium gives up its single electron on the outer energy shell to chlorine which readily accepts it and fills its outer shell to make 8  forming ionic bonds and is thus  the two are completely stable and cannot explode or react in any other way because the outer shell of each of them is now filled with 8 electrons.


7 0
2 years ago
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