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AleksAgata [21]
3 years ago
7

1. A dining hall had a total of 25 tables-some long rectangular tables and some round

Chemistry
1 answer:
TEA [102]3 years ago
7 0

x = 20 long tables

y = 5 round table

Explanation:

We have the following system of equations:

x + y = 25

8x + 6y = 190

From the first equation we have:

x = 25 - y

And we replace x in the second equation:

8(25 - y) + 6y = 190

200 - 8y + 6y = 190

200 - 2y = 190

200 - 190 = 2y

10 = 2y

y = 5

Now we insert the value of y in the next equation:

x = 25 - y

x = 25 - 5

x = 20

Learn more about:

system of equations

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Using off road vehicles does help contribute to the process of erosion.
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Which of the following could happen when infrared radiation is absorbed by a molecule ?
Leto [7]

Answer:

       E) Intramolecular bond angles change

Explanation:

Infrared Radiation:

IR is electromagnetic radiations. The wavelength i.e. 700nm to 1000 mm of infrared is longer than invisible light and Its frequency is lower than light, that's why it is invisible to light.

  • When IR radiation strike the molecule it absorbed by this molecule.
  • This radiation used to identify and study chemicals.
  • Infrared radiation interact with intra-bonds of the molecule.
  • Bonds in the molecules have vibrational translational and rotational movements
  • Due to these vibration, rotation and translation movement it absorb a radiation of specific frequency and wavelength
  • These movements of bond are very small and absorbs radiations of very low frequency
  • So when Infrared light or radiation absorbed the intra-bonds of the molecule get affected and angles of these bonds changes.
  • As the frequency of the absorbed radiation matches the frequency of the bond that vibrates.

So

The correct option is option E

       E) Intramolecular bond angles change

* Note:

it couldn't be option A as the frequency of IR is not enough to rotate a whole molecule

It Couldn't be option B as IR rations are electromagnetic radiation of longer wave length so it one can not see it with light so how it will glow a molecule

It also not could be the option C as for the excitation of electrons require much higher energy.

It also not the option D as nuclear magnetic spin is associated with nuclear magnetic radiation that are much different from IR.

4 0
3 years ago
How many moles are in a 12.0 g sample of NiC12
Nady [450]

Answer:

0.17 moles

Explanation:

In the elements of the periodic table, the atomic mass = molar mass. <u>Ex:</u> Atomic mass of Carbon is 12.01 amu which means molar mass of Carbon is also 12.01g/mol.

In order to find the # of moles in a 12 g sample of NiC-12, we will need to multiply the number of each atom by its molar mass and then add the masses of both Nickel and C-12 found in the periodic table:

  • Molar Mass of Ni (Nickel): 58.69 g/mol
  • Molar Mass of C (Carbon): 12.01 g/mol

Since there's just one atom of both Carbon and Nickel, we just add up the masses to find the molar mass of the whole compound of NiC-12.

  • 58.69 g/mol of Nickel + 12.01 g/mol of Carbon = 70.7 g/mol of NiC-12

There's 12g of NiC-12, which is less than the molar mass of NiC-12, so the number of moles should be less than 1. In order to find the # of moles in NiC-12, we need to do some dimensional analysis:

  • 12g NiC-12 (1 mol of NiC-12/70.7g NiC-12) = 0.17 mol of NiC-12
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<em>P.S. C-12 or C12 just means that the Carbon atom has an atomic mass of 12amu and a molar mass of 12g/mol, or just regular carbon.</em>

5 0
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Alja [10]

Answer:its b

Explanation:

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Answer:

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b) boil it at 78.3

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c) sum up the answers from the two calculations above. Be sure to change the J from the first calc into kJ

Explanation:

3 0
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