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3 years ago

What are the main classifications or categories of elements in the periodic table?

1 answer:

5 0

Alkali metals, Alkaline Earth metals, Transition metals, Basic metals, semi metals or metalloids, Non-metals, Halogens, Noble gases, Lanthanides and Actinides.

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HURRYYY!!!! Convert 7.13 x 10^28 atoms of calcium (Ca) to moles of calcium.

puteri [66]

Answer:

<h2>118,438.5 moles</h2>

Explanation:

To find the number of moles in a substance given it's number of entities we use the formula

$n = \frac{N}{L}\\$

where n is the number of moles

N is the number of entities

L is the Avogadro's constant which is

6.02 × 10²³ entities

From the question we have

$n = \frac{7.13 \times {10}^{28} }{6.02 \times {10}^{23} } \\ = 118438.538...$

We have the final answer as

<h3>118,438.5 moles</h3>

Hope this helps you

4 0

3 years ago

The balls in a modeling kit representing different elements are often distinguished by color. however, there are other ways to i

nika2105 [10]

The size of the atoms a and the number of holes in the atoms can be used to decode the element.

<h3>What are models?</h3>

A model is a miniature depiction of reality. Molecular models often consists of boxes that contain balls which are used to represent elements. In common parlance, the color is used to show the type of element.

Apart from the color, the size of the atoms a and the number of holes in the atoms can be used to decode the element.

Learn more about molecular models:brainly.com/question/156574

#SPJ1

5 0

2 years ago

If the wavelength of purple light is 400 x 10^-9 m, what is the frequency?

FromTheMoon [43]

The frequency : a) 7.5 x 10¹⁴ /s

<h3>Further explanation</h3>

Radiation energy is absorbed by photons

The energy in one photon can be formulated as

$\large{\boxed{\bold{E\:=\:h\:.\:f}}}$

Where

h = Planck's constant (6,626.10⁻³⁴ Js)

f = Frequency of electromagnetic waves (/s or Hz)

f = c / λ

c = speed of light

= 3.10⁸ m/s

λ = wavelength

The wavelength(λ) of purple light is 400 x 10⁻⁹ m, so the frequency :

$\tt f=\dfrac{c}{\lambda}\\\\f=\dfrac{3.10^8~m/s}{4.10^{-7}m}\\\\f=\boxed{\bold{7.5.10^{14}}/s}$

3 0

3 years ago

The standard internal energy change for a reaction can be symbolized as Δ U ∘ rxn or Δ E ∘ rxn . For each reaction equation, cal

rosijanka [135]

Answer : The internal energy change is, -506.3 kJ/mol

Explanation :

Formula used :

$\Delta H=\Delta U+\Delta n_gRT$

or,

$\Delta U=\Delta H-\Delta n_gRT$

where,

$\Delta H$ = change in enthalpy = $-511.3kJ/mol=-511300.0J/mol$

$\Delta U$ = change in internal energy = ?

$\Delta n_g$ = change in moles

Change in moles = Number of moles of product side - Number of moles of reactant side

According to the reaction:

Change in moles = 0 - 2 = -2 mole

That means, value of $\Delta n_gRT$ = 0

R = gas constant = 8.314 J/mol.K

T = temperature = $25^oC=273+25=298K$

Now put all the given values in the above formula, we get

$\Delta U=\Delta H-\Delta n_gRT$

$\Delta U=(-511300.0J/mol)-[-2mol\times 8.314J/mol.K\times 298K$

$\Delta U=-511300.0J/mol+4955.144J/mol$

$\Delta U=-506344.856J/mol=-506.3kJ/mol$

Therefore, the internal energy change is -506.3 kJ/mol

6 0

3 years ago

Describe the effects of anaerobic respiration on the body and explain the effects on the body

anzhelika [568]

Answer:

In anaerobic respiration, glucose breaks down without oxygen. The chemical reaction transfers energy from glucose to the cell. Anaerobic respiration produces lactic acid, rather than carbon dioxide and water. Unfortunately this can lead to painful muscle cramps.

please mark my anSwEr as brainlist

5 0

3 years ago

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