What is the shape of pure carbon fullerenes?

What kind of ocean ecosystem did the author of this text ask questions about

shutvik [7]

Forests and prairies are examples of ecosystems on land. An ecosystem is a community of living things. Members survive by interacting with each other and with their environment. At first glance, the ocean seems like one big ecosystem.

5 0

3 years ago

the atomic number of four elements p,q,r,s are 6,8,10 and 12 respectively. the two elements which can bond ionically are:

denis-greek [22]

Answer:

The atomic numbers of four elements A, B, C, and D are 6,8,10, and 12 respectively. The two elements which can react to form ionic bonds (or ionic compounds) are B (8= 2,6) and D (12 =2,8,2). So D donates its two electrons to B to fulfill their octet.

Explanation:

6 0

2 years ago

Arrange the following H atom electron transitions in order of decreasing wavelength of the photon absorbed or emitted:

Katyanochek1 [597]

The decreasing order of wavelengths of the photons emitted or absorbed by the H atom is : b → c → a → d

Rydberg's formula :

$\frac{1}{\lambda} = R_h (\frac{1}{n_1^2}-\frac{1}{n_2^2} )$ ,

where λ is the wavelength of the photon emitted or absorbed from an H atom electron transition from $n_1$ to $n_2$ and $R_h$ = 109677 is the Rydberg Constant. Here $n_1$ and $n_2$ represents the transitions.

(a) $n_1$ =2 to $n_2$ = infinity

$\frac{1}{\lambda} = 109677\times (\frac{1}{2^2}-\frac{1}{\infty^2} )$ = 109677/4 [since 1/infinity = 0] Therefore, $\lambda$ = 4 / 109677 = 0.00003647 m

(b) $n_1$ =4 to $n_2$ = 20

$\frac{1}{\lambda} = 109677\times (\frac{1}{4^2}-\frac{1}{20^2} )$ = 6580.62

Therefore, $\lambda$ = 1 / 6580.62 = 0.000152 m

(c) $n_1$ =3 to $n_2$ = 10

$\frac{1}{\lambda} = 109677\times (\frac{1}{3^2}-\frac{1}{10^2} )$ = 11089.56

Therefore, $\lambda$ = 1 / 11089.56 = 0.00009 m

(d) $n_1$ =2 to $n_2$ = 1

$\frac{1}{\lambda} = 109677\times (\frac{1}{2^2}-\frac{1}{1^2} )$ = - 82257.75

Therefore, $\lambda$ = 1 /82257.75 = - 0.0000121 m

[Even though there is a negative sign, the magnitude is only considered because the sign denotes that energy is emitted.]

So the decreasing order of wavelength of the photon absorbed or emitted is b → c → a → d.

Learn more about the Rydberg's formula athttps://brainly.com/question/14649374

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8 0

1 year ago

Even though so much energy is required to form a metal cation with a 2+ charge, the alkaline earth metals form halides with gene

nasty-shy [4]

The ∆Hrxn of the reaction is -394.5kJ/mol.

<h3>What is alkaline earth metal? </h3>

The alkaline earth metals are those elements which correspond to group 2 of the modern periodic table.

All elements of this group forms a cation of +2 charge.

The other elements of this group are:

Beryllium, Magnesium, Calcium, Strontium, Barium, and Radium.

<h3>What is Halogen? </h3>

The Halogen elements are present in group 17 of the modern periodic table.

All elements of this groups forms anions of -1 charge.

The elements of this group are:

Fluorine, Chlorine, bromine, iodine, and astatine.

∆Hrxn = ∆H(bond broken) - ∆H(bond formed)

We have following data of bond energy in kJ/mol:

Mg—Mg = 738

Cl—Cl = -349

Mg—Cl = 783.5

Since, one mole of Mg react with one mole of Cl atom to form one mole of MgCl

∆Hrxn = 738-349-783.5

∆Hrxn = -394.5kJ/mol.

Thus, we concluded that the ∆Hrxn of the reaction is -394.5kJ/mol.

learn more about bond energy:

brainly.com/question/13526463

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3 0

1 year ago

Write the net ionic equation for the precipitation of calcium sulfide from aqueous solution

Fantom [35]

Answer:

Answer is Ca2+(aq)+S2-(aq)=>CaS(s)

Explanation:

I hope it's helpful!

7 0

3 years ago