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2 years ago

Which of the following best describes a mole as used in chemistry?

Chemistry

1 answer:

bazaltina [42]2 years ago

8 0

Answer: a very large number of objects

Explanation: Mole is the amount of objects and it has the usually Avogadro number of atoms, molecules, ions, etc in chemistry

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Which atom, selenium (Se) or Arsenic (As), has the higher electron affinity and why?

IrinaVladis [17]

Answer:

5. Selenium, because it does not have a stable, half-filled p subshell and adding an electron does not decrease its stability.

Explanation:

Electron affinity is the amount of energy released when an isolated gaseous atom accepts electron to form the corresponding anion.

Selenium:-

The electronic configuration of the element is:-

$[Ar]3d^{10}4s^24p^4$

Arsenic:-

The electronic configuration of the element is:-

$[Ar]3d^{10}4s^24p^3$

The 4p orbital in case of arsenic is half filled which makes the element having more stability as compared to selenium.

Thus, selenium has higher electron affinity because adding electron does not decrease the stability as in case of arsenic.

8 0

2 years ago

Balance the following equation: __Ch4+__O2→__CO2+__H2O

konstantin123 [22]

Answer:

1,2,1,2

Explanation:

You would need only one of the CH4 but 2 of the O2 then 1 CO2 and 2 H2O on each side of the equation you now have 1 carbon, 4 hydrogen, and 4 oxygen.

3 0

2 years ago

Which Of These Is An Indication That A Chemical Reaction Has Occurred?

nikdorinn [45]

Answer:

Correct option is D. Formation Of A Gas

Explanation

The main indication of chemical is that new substances are formed which have different composition than reactant.

Freezing of a substance: As in this case composition remained same, so we cant say, chemical reaction is take place, like when water freezes, it composition is same as water , so it is only its physical properties, not chemical.

Melting of a substance: As in this case composition remained same, so we cant say, chemical reaction is take place, like when ice melts, composition of water remained same , so it its physical properties, not chemical.

Boiling of a substance: As in this case composition remained same, so we cant say, chemical reaction is take place, like when water boils and become vapors, composition of water and vapors remained same , so it its physical properties, not chemical properties which show its chemical reaction.

Formation of gas:

In this case, chemical reaction take place. In chemical reactions, new substance are formed whose composition is different from reactants.

6 0

3 years ago

Read 2 more answers

One of the postulates of bohr's atomic model of a moving electron is that angular momentum of a moving electron is quantized. Ex

oksano4ka [1.4K]

The angular momentum of an electron in the third Bohr orbit of a hydrogen atom is given by mvr=3h÷2π

<h3>What is momentum?</h3>

Momentum is defined as the amount of motion occurring in something that is moving, or the force that drives something forward to keep it moving.

Bohr never assumed stable electronic orbits with the electronic angular momentum quantized as

l=mvr = $\frac{nh}{2pi}$

Quantization of angular momentum means that the radius of the orbit and the energy will be quantized as well.

Bohr assumed that the discrete lines seen in the spectrum of the hydrogen atom were due to transitions of an electron from one allowed orbit/energy to another.

Learn more about momentum here:

https://brainly.in/question/38837394

#SPJ1

5 0

1 year ago

Physical Meaning of pKa Which of the following aqueous solutions has the lowest pH: 0.1 M HCl; 0.1 M acetic acid (pKa = 4.86); 0

ser-zykov [4K]

Answer:

The solution with the lowest pH is 0.1 M HCl.

Explanation:

Since the three solutions have the same concentration (0,1M) it is only necessary to look at the pKa of each solution.

Also, knowing that a higher pKa means a lower Ka, because pKa = -Log (Ka). Thus, a lower Ka means a lower concentration of protons with a higher pH ( pH = -Log [H+].

The HCl doesn't have a pKa because is a strong acid that dissociates completely. Therefore, this solution produces a lower pH. Looking at the pKa of acetic acid and formic acid solutions, the second with the lowest pH is the formic acid solutions and the higher pH is for the acetic acid solution.

3 0

3 years ago