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2 years ago

Which of the following does not describe elements?

2 answers:

6 0

The statement that does not describe elements would be that they can be separated by a chemical reaction. This is not the case, an element is a pure substance that can't be degraded into any other constituent that would form it. They are building blocks composed by atoms.

shusha [124]2 years ago

3 0

Answer: Option (b) is the correct answer.

Explanation:

Elements are defined as the substance which contain same type of atoms.

An element cannot be divided into simpler substances by any physical or chemical means.

For example, a piece of aluminium will contain only atoms of aluminium.

The periodic table contains all the elements present in nature.

Thus, we can conclude that out of the given options the statement they can be separated by a chemical reaction, does not describe elements.

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A 63 kg object needs to be lifted 7 meters in a matter of 5 seconds. Approximately how much horsepower is required to achieve th

Digiron [165]

A. is the correct answer!

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1 year ago

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According to the quantum-mechanical model for the hydrogen atom, which electron transition produces light with the longer wavele

LekaFEV [45]

Answer:

Explanation:

The main task here is that there are some missing gaps in the above question that needs to be filled with the appropriate answers. So, we are just going to do rewrite the answer below as we indicate the missing gaps by underlining them and making them in bold format.

SO; In the quantum-mechanical model of the hydrogen atom.

As the n level increases. the energy increases and thus levels are closer to each other. Therefore, the transition 3p→2s would have a greater energy difference than the transition from 4p→3p.

$Energy \ and \ wavelength \ are \ inversely \ proportional , \ so \ the \ \mathbf{ 4p\to 3p} \ transition \ would$ $produce \ a \ longer \ wavelength.$

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1 year ago

El cuerpo humano tiene unos 6 billones de células (6,0x1012) y la población de la Tierra es de unos 8 000 millones de personas.

zloy xaker [14]

Answer:

En toda la población del mundo hay 0.0797 moles de células

Explanation:

1.0 mol of cells = 6.022 * 10∧23 cells

X mol of cells = 6.0 * 10∧12 cells

- X is cleared to find out how many moles of cells are in a human body:

X = 6.0 * 10∧12 cells / 6.022 * 10∧23 cells

X = 9,963 * 10∧-12 moles of cells per person

In the world there are 8 * 10∧9 people, how many moles in total will there be?

8 * 10∧9 people * 9,963 * 10∧-12 moles of cells per person =

0.0797 moles of molecules in the entire population of the earth.

4 0

2 years ago

If MnSO4 → MnO+SO3 is not a synthesis reaction, then what type of reaction is it?

mezya [45]

Answer: It would be decomposition :)

8 0

1 year ago

Read 2 more answers

Calculate the enthalpy change associated with the conversion of 25.0 grams of ice at -4.00 °C to water vapor at 110.0 °C. The sp

satela [25.4K]

Answer : The enthalpy change is, 104.5327 KJ

Solution :

The conversions involved in this process are :

$(1):H_2O(s)(-277K)\rightarrow H_2O(s)(273K)\\\\(2):H_2O(s)(273K)\rightarrow H_2O(l)(273K)\\\\(3):H_2O(l)(273K)\rightarrow H_2O(l)(373K)\\\\(4):H_2O(l)(373K)\rightarrow H_2O(g)(373K)\\\\(5):H_2O(g)(373K)\rightarrow H_2O(g)(383K)$

Now we have to calculate the enthalpy change.

$\Delta H=[m\times c_{p,s}\times (T_{final}-T_{initial})]+n\times \Delta H_{fusion}+[m\times c_{p,l}\times (T_{final}-T_{initial})]+n\times \Delta H_{vap}+[m\times c_{p,g}\times (T_{final}-T_{initial})]$

where,

$\Delta H$ = enthalpy change = ?

m = mass of water = 25 g

$c_{p,s}$ = specific heat of solid water = 2.09 J/gk

$c_{p,l}$ = specific heat of liquid water = 4.18 J/gk

$c_{p,g}$ = specific heat of liquid water = 1.84 J/gk

n = number of moles of water = $\frac{\text{Mass of water}}{\text{Molar mass of water}}=\frac{25g}{18g/mole}=1.39mole$

$\Delta H_{fusion}$ = enthalpy change for fusion = 6.01 KJ/mole = 6010 J/mole

$\Delta H_{vap}$ = enthalpy change for vaporization = 40.67 KJ/mole = 40670 J/mole

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

$\Delta H=[25g\times 4.18J/gK\times (273-277)k]+1.39mole\times 6010J/mole+[25g\times 2.09J/gK\times (373-273)k]+1.39mole\times 40670J/mole+[25g\times 1.84J/gK\times (383-373)k]$

$\Delta H=104532.7J=104.5327KJ$ (1 KJ = 1000 J)

Therefore, the enthalpy change is, 104.5327 KJ

5 0

1 year ago