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masya89 [10]
3 years ago
8

Which of the following correctly describes a compound?

Chemistry
1 answer:
Nutka1998 [239]3 years ago
3 0

A compound is a pure substance formed by the chemical combination of two or more different elements.


A compound may be splitted into simpler substances by chemical reactions, and has different properties to those of the elements that form it.


The composition of a compound is fixed: every piece of a compound has the same kind of atoms, bonded in the same way and proportion.


Some examples of compounds are H₂O, NaCl, H₂O₂, CH₃COOH. As you see, they have a chemical formula which states the kind and number of the atoms that form them.


They are different to mixtures, which are formed by two or more compounds, in a variable proportion, and can be separated by physical media. Some examples of mixtures are the solutions (e.g. NaCl dissolved in H₂O), and some solid mixtures (e.g. a mixture of marbles and sand).

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An energy of 6.8 x 10^-19 J/atom is required to cause an aluminum atom on a metal surface to lose an electron.
Nana76 [90]

Wavelength of the light is 2.9 × 10⁻⁷ m.

<u>Explanation:</u>

Planck - Einstein equation shows the relationship between the energy of a photon and its frequency, and they are directly proportional to each other and  it is given by the equation as E = hν,

where E is the energy of the photon

h is the Planck's constant = 6.626 × 10⁻³⁴ J s

ν is the frequency

From the above equation, we can find the frequency by rearranging the equation as,

ν = $ \frac{E}{h} = $ \frac{6.8 \times 10^{-19}}{6.626\times10^{-34}} = 1.03\times10^{15} s^{-1}

Now the frequency and the wavelength are in inverse relationship with each other.

ν × λ = c

It can be rearranged to get λ as,

λ = c / ν

 = $\frac{3\times 10^{8} ms^{-1}}{1.03\times10^{15}s^{-1}} = 2.9\times 10^{-7} m

So wavelength is 2.9 × 10⁻⁷ m.

6 0
3 years ago
What is the osmotic pressure, in torr, of a 3.00% solution of NaCl in water when the temperature of the solution is 45 ºC? Enter
Anit [1.1K]

213034 torr is the osmotic pressure.

Explanation:

osmotic pressure is calculated by the formula:

osmotic pressure= iCrT

where i= no. of solute

c= concentration in mol/litre

R= Universal Gas constant

T = temp

It is given that solution is 3% which is 3gms in 100 ml.

let us calculate the concentration in moles/litre

3gm/100ml*1000ml/1L*1mol NaCl/55.84g NaCl

= 5.372 gm/litre

Putting the values in the formula,                   Temp in Kelvin 318.5K

osmotic pressure= 2*5.372*0.083 * 318.5                 Gas constant  0.083

                              = 284.023 bar or 213018 torr.                 c=  5.372 moles/L                                                                              

                                                                                    i=2 for NaCl

4 0
3 years ago
5. How many elements do we have in Octane?
jekas [21]

Answer:

2 elements

Explanation:

Octane is composed of carbon and hydrogen atoms.

3 0
3 years ago
At high pressures and moderate temperatures nitric oxide gas disproportionates rapidly according to the reaction 3NO(g) ⇌ N2O(g)
Pie

Answer:

3.8 x 10⁵

Explanation:

For the equilibrium :  3NO(g) ⇌ N2O(g) + NO2(g), the equilibrium constant in the terms of the concentrations of the gases in mol/L is

Kc = (NO) (N2O)/ (NO) ³   where (NO), (N2O) , (NO2) are the concentrations of the gases in mol/L . So

K= (x mol/ 1 L) (x mol/1L) / (7.5 x 10⁻⁶ mol /1 L) ³

x  = mol of NO and NO2 at equilibrium

we have that

K = x²/ 7.5 x 10⁻⁶ = 1.9 x 10¹⁶

x = √ (7.5 x 10⁻⁶ x  1.9 x 10¹⁶) = 3.8 x 10⁵

∴ (N2O) = 3.8 x 10⁵

3 0
3 years ago
Read 2 more answers
A hydrogen fuel cell is an electrochemical reactor in which oxygen and hydrogen gas are reacted to produce energy. Rather than c
Contact [7]

Answer:

(d) Why is the fuel cell in Question (c) described as an alkaline fuel cell? (e) Another type of fuel cell uses methanol instead of hydrogen.

Explanation:

6 0
3 years ago
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