Which is one way that scientists communicate the results of an experiment?

Answer:

Explanation:

250 cm^3 of 0.2 moldm-3 H2SO4 can be prepared from 150cm^3 of 1.0 moldm^-3 by dilution.

150cm^3 of the 1.0 moldm^-3 stock solution is measured out using a measuring cylinder and transferred into a 250 cm^3 standard volumetric flask and made up to mark. The resulting solution is now 250cm^3 of 0.2 moldm-3 H2SO4.

Answer:

The answer is "1".

Explanation:

It is the lone pairs at, which the central atom provides the molecular and the polarity. It is only for substances with just a central atom, for which the molecules with only one central atom and only one of the solitary paired were required, that's why in this question the "1" is the correct answer.

Answer: the density of the bread is 0.2g per 1 cm3

Explanation: density is defined as mass per volume d= m/v so we can calculate 500g÷ 2500cm3= 0.2g/1 cm3

Answer:

Percent yield = 21%

Explanation:

Find:

Percent yield

Computation:

1 mol O₂ produces 2 mol NO₂

So,

10 mol O₂ produces 20 mol NO₂

Percent yield = [Actual yield / Theoretical yield]100

Percent yield = [4.2 / 20]100

Percent yield = 21%

The percent yield for the reaction is 21%

From the question,

We are to determine the percent yield for the reaction.

First, we will determine the theoretical yield for the reaction

From the given balanced chemical equation for the reaction

2 NO (g) + O₂ (g) → 2 NO₂ (g)

This means,

2 moles of NO reacts with 1 mole of O₂ to produce 2 moles of NO₂

From the given information,

Number of moles of O₂ that reacted = 10.0 moles

Since,

2 moles of NO reacts with 1 mole of O₂ to produce 2 moles of NO₂

Then,

2×10 moles of NO will be required to react with the 10 moles of O₂ to produce 2×10 moles of NO₂

That is,

20 moles of NO will be required to react with the 10 moles of O₂ to produce 20 moles of NO₂

∴ 20 moles of NO₂ will be produced during the reaction.

This is the theoretical yield

Now, for the percent yield of the reaction,

Using the formula

[tex]Percent\ yield = \frac{Actual\ yield }{Theoretical\ yield} \times 100\%[/tex]

From the question

Actual yield = 4.2 mole

∴ Percent yield for the reaction = [tex]\frac{4.2}{20 }\times 100\%[/tex]

Percent yield for the reaction = [tex]\frac{420}{20}\%[/tex]

Percent yield for the reaction = 21%

Hence, the percent yield for the reaction is 21%

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Answer:

Condensation starts to occur throughout the liquid instead of just on the surface.

Answer:

30 g 0f NaOH.

Explanation:

The following data were obtained from the question:

Molarity of NaOH = 0.25 M

Volume = 3 dm³

Mass of NaOH =?

Next, we shall determine the number of mole of NaOH present in 3 dm³ of 0.25 M NaOH solution.

This can be obtained as follow:

Molarity of NaOH = 0.25 M

Volume = 3 dm³

Mole of NaOH =?

Molarity = mole /Volume

0.25 = mole of NaOH/3

Cross multiply

Mole of NaOH = 0.25 × 3

Mole of NaOH = 0.75 mole

Finally, we shall determine the mass of NaOH as follow:

Mole of NaOH = 0.75 mole

Molar mass of NaOH = 23 + 16 + 1 = 40 g/mol

Mass of NaOH =.?

Mole = mass /Molar mass

0.75 = mass of NaOH /40

Cross multiply

Mass of NaOH = 0.75 × 40

Mass of NaOH = 30 g

Therefore, 30 g 0f NaOH is present in the flask.

The mass of NaOH in 0.25 M sample has been [tex]\rm\bold{ 30\;g/dm^3}[/tex].

The molarity has been defined as moles of sample present in a liter of solution.

The molarity of given NaOH solution has been 0.25 M. It has been stating that 0.25 moles of NaOH has been present in a liter of solution.

The mass of sample present in 1 cubic decimeter has been the mass of sample in a liter of solution as:

[tex]\rm 1\;dm^3=1\;L[/tex]

The molarity (M) has been given as:

[tex]M=\dfrac{\text {mass}}{mwt}\;\times\;\dfrac{1}{V(L)}[/tex]

Where, the molarity of NaOH sample has been, [tex]M=0.25\;\text M[/tex]

The molar mass of NaOH has been, [tex]mwt=40\;\text {g/mol}[/tex]

The volume of solution has been, [tex]V=3 \;\text L[/tex]

Substituting the values for mass of NaOH:

[tex]0.25=\dfrac{mass}{40}\;\times\;\dfrac{1}{3} \\mass=0.25\;\times\;40\;\times\;3\\mass=30\;\text g[/tex]

The mass of NaOH in 0.25 M sample has been [tex]\rm\bold{ 30\;g/dm^3}[/tex].

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Answer: Easy,the answer is the letter D

Answer:

1.85 × 10⁻⁶

Explanation:

0.0003 ÷ 162 = 1.851851852 × 10⁻⁶ ⇒ 1.85 × 10⁻⁶

Hope that helps.

The significant figure in the answer should be one here, since the number 0.0003 contains only one significant figure. Hence, the answer is 2 × 10⁻⁶.

Significant figures are digits in a quantity with certain values along with some uncertain digits. The counting of significant figures of a number should follow some rules.

The zeros after the decimal point which is not following a nonzero number are not significant. Therefore, there is only one significant figure in the number 0.0003.

For any arithmetic operation, the number of significant figures in the result should be equal to the one in operation that is with least significant figures.

Here.  162 have 3 significant figures. Therefore, the result should contain only one significant figure.

0.0003 /162 = 1.85  × 10⁻⁶.

Then the result with correct significant figures is rounded to 2 × 10⁻⁶.

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Answer: Thus X is Plutonium

Explanation:

Alpha Decay: In this process, a heavier nuclei decays into lighter nuclei by releasing alpha particle. The mass number is reduced by 4 units and atomic number is reduced by 2 units.

General representation of alpha decay :

[tex]_{Z}^{A}\textrm{X}\rightarrow _{Z-2}^{A-4}\textrm{Y}+_2^4\textrm{He}[/tex]

where Z = atomic number

A= mass number

X and Y = atomic symbol of elements

[tex]_{Z}^{A}\textrm{X}\rightarrow _{92}^{235}\textrm{U}+_2^4\textrm{He}[/tex]

Thus [tex]_{94}^{239}\textrm{Pu}\rightarrow _{92}^{235}\textrm{U}+_2^4\textrm{He}[/tex]

Thus X is Plutonium with atomic number 94 and mass number 239

Answer:

the answer is D on edge

Explanation:

Answer:

4. 915 cm^3

Explanation:

Length = 22.0cm

Breadth = 13 cm

Thickness = 3.2 cm

Volume = Length * Breadth * Thickness

Volume =  22 * 13 * 3.2

Volume = 915.2 cm^3

Volume = 915cm^3. The correct option is option 4.

Answer:

The statement that best describes pseudoscience is that it lacks a process for collecting data

Answer: not a branch of science and involves beliefs and opinions

Explanation:

The volume of the box taking significant figures into account is 38.8125 ≈39 cm³.

The amount of space occupied by a three-dimensional object or region of space, expressed in cubic units (cm³).

It means, the amount of three dimensional space that a closed figure can occupy is measured by its volume.

Formula for volume=length ×breadth ×height

To calculate the volume of the box,

volume=length × breadth × height

volume=4.5×5.750×1.50

volume=38.8125   ≈39 cm³.

Hence, the volume of the box taking significant figures into account is 38.8125 ≈39 cm³.

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Answer: 22 neutrons

Explanation: 40 is the mass number = atomic mass = total number of protons and neutrons in atomic nucleus

18 is the number of protons in the nucleus of this atom

Then 40 - 18 = 22 neutrons

and this is Argon

Answer:

When an object is allowed to fall,the concentrated gravitational potential energy is converted into the kinetic energy of motion. if there is no air resistance or other restrictions all of the potential energy will be converted to kinetic energy when the object has fallen the distance H

Explanation

When an object is allowed to fall,the concentrated gravitational potential energy is converted into the kinetic energy of motion. if there is no air resistance or other restrictions all of the potential energy will be converted to kinetic energy when the object has fallen the distance H

Answer:

Storage battery oe cell

Explanation:

The storage battery or cell is a device that coverts chemical energy into light energy when required.

During charging of battery, there is some chemical changes in the battery and absorb energy. The absorbed energy is converted into electrical energy when connected to an external load.

Hence, the correct answer is "Storage battery or cell".

Answer:

A) Ca(s) + C(s) + 3/2 O₂(g) → CaCO₃(s)

Explanation:

Standard enthalpy of formation of a chemical is defined as the change in enthalpy durin the formation of 1 mole of the substance from its constituent elements in their standard states.

The consituent elements of calcium carbonate, CaCO₃, in their standard states (States you will find this pure elements in nature), are:

Ca(s), C(s) and O₂(g)

That means, the equation that represents standard enthalpy of CaCO₃ is:

Is the equation that has ΔH° = -1207kJ/mol

Answer:

830 mL or 0.83L

Explanation:

Answer:

Synthetic

Explanation:

I just took the quiz and got it right

Answer:

A- Synthetic

Explanation:

just took the quiz

Answer:

When changing state of aggregation, the particles change their kinetic energy, decreasing or increasing, if their kinetic energy decreases the collision between the particles is less, and therefore less heat is released and more space will exist between them, this is an example of the states of aggregation that occupy large expandable volumes such as gas.

As the particles get closer, the molecules are closer and collide in a greater way, thus generating that the kinetic energy increases, the friction also and these particles are closer to each other, compressing the space and limiting their movement up to a point.

Explanation:

The states are three, solid liquid and gaseous-

In the solid state there is less distance between the particles, greater density of the body and greater force of friction or collision.

On the other hand, in the solid state the particles are more distended but up to a limit they expand, different from the gaseous state that their particles expand more and without a limit.

The states are modified according to the different temperatures that the body undergoes, at a higher temperature a higher kinetic energy and greater friction are usually reached, generating relaxed states such as liquid and gas, and at lower temperatures it is the reverse effect.

So, neon has a molar mass of 20.18 g/mol , which means that every mole of neon has a mass of 20.18 g . Now, you know that one mole of any element contains exactly 6.022⋅1023 atoms of that element - this is Avogadro's number.

Hope this helped

Answer:

• 1.62432 moles of nitrogen

• Tire Pressure: 2.74 * 10⁵ Pa

• The tires will burst

• Pressure: 244 kPa

Explanation:

• We can determine the number of moles of nitrogen using the formula pV = nRT, where p = pressure, V = volume, n = number of moles, R = gas constant, and T = absolute temperature.

Now remember we have our initial pressure in kilopascals so let's convert to pascals (249 pascals). The volume is given in liters, so let's convert into m². And the initial temperature is given in Celsius ⇒ our absolute temperature in Kelvins.

[tex]\mathrm{p\:}=\mathrm{249 kPa\:} = \mathrm{2.49 * 10^5\:},\\\mathrm{15.6L\:} =\mathrm{0.0156m^2\:},\\\mathrm{R\:}=\mathrm{8.314J/mol*K\:},\\\mathrm{T\:}=\mathrm{21C\:} + \mathrm{273\:}=\mathrm{294K\:}[/tex]

Respectively the moles of nitrogen in each tire should be:

[tex]\mathrm{n\:}=\mathrm{pV/RT\:}=\mathrm{(2.49*10^5)(0.0156)/(8.314)(294)\:}=\frac{\left(2.49\cdot \:10^5\right)\left(0.0156\right)}{\left(8.134\right)\left(294\right)}=\frac{3884.4}{2391.396}\\[/tex]

[tex]= 1.62432\dots \mathrm{moles\:}\mathrm{of\:}\mathrm{nitrogen\:}[/tex]

• We can solve this part similarly. All our values will be the same, besides the temperature, as we have to consider both the initial and final temperature here.

[tex]\mathrm{T_2\:}=\mathrm{51C+ 273\:} }=\mathrm{324K\:} }[/tex] -

[tex]\mathrm{p_2\:}=\mathrm{(2.49*10^5)(324)/(294)\:} }=\frac{\left(2.49\cdot \:10^5\right)\left(324\right)}{294}=\frac{40338000}{147}=274408.16326\dots[/tex]

[tex]=2.74408.16326*10^5\dots\mathrm{Pa}[/tex]

• The text mentions that the tires will burst when the internal pressure reaches 269kP. From part #2 we know that the final pressure will be, in kilopascals, 274kP. As 274 > 269, the tires will burst in Death Valley.

• We would want the final temperature = breaking pressure. Therefore,

[tex]\mathrm{p_2\:}=\mathrm{(269)(294)/(324)\:} }=\frac{79086}{324}=\frac{13181}{54}=244.09259\dots\mathrm{kPa\:} }[/tex]

Answer:

1) law of conservation of mass

2) volatile

3) endothermic

4) chemical property

5) exothermic

6) density

7) physical change

8) chemical change

9) physical property

10) chemical reaction

Answer:

The difference between the two is that plant have three extra "components" than animal. The three extra components include a different sort of vacuole, chloroplast, and a cell wall.

Explanation:

Answer:

metals are are solids and has high melting point( except mercury and can also conduct heat and electricity, where non-metals may be solids also but,is brittle such as :diamonds etc... Its a bad conductor for heat and has low melting points

Answer:

activasion energy

Explanation:

Diamond and graphite are allotropes of carbon  and have various differences in their physical properties.

Explanation:

Diamond:

Graphite:

This is the comparison of the physical properties of two forms of carbon: diamond and graphite

Carbon and Diamond are allotropes of carbon having  different physical properties.

In diamond there is a three dimensional network of strong covalent bonds. This makes diamond extremely hard.

On the other hand, in graphite there are flat layers of carbon atoms. These layers are held by weak van der Waal’s forces and hence can easily slip one over the other. This makes graphite extremely soft and slippery.

In diamond all the four valence electrons carbon are involved in covalent bonds and are not free to conduct electricity. This makes diamond a bad conductor of electricity. In graphite, the fourth valence electron is relatively free, can move from one carbon atom to the other in a layer, and hence is responsible for conducting electricity. Hence, graphite is a good conductor of electricity.

In diamond as well as in graphite carbon atoms are held by strong net work of covalent bonds. Therefore, both have very high melting points.

Therefore, we can compare the physical  properties of carbon and diamond.

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Explanation:

For most folks, a thermometer reading around 98.6 degrees Fahrenheit (37 degrees Celsius) means their body temperature is normal. Now, two scientists have an idea why our bodies, as well as those of most other mammals, consistently run at that temperature : A toasty body temperature helps keep nasty fungal infections at bay.

"One of the mysteries about humans and other advanced mammals has been why they are so hot compared with other animals," said study co-author Arturo Casadevall, professor and chair of microbiology and immunology at Albert Einstein College of Medicine of Yeshiva. "This study helps to explain why mammalian temperatures are all around 98.6 degrees Fahrenheit."

Casdevall's previous work showed that the number of fungal species that can thrive and, therefore, infect an animal declines by 6 percent for every 1.8 degree F (1 C) rise in temperature. This, he claimed, is why reptiles , amphibians and other cold-blooded animals are susceptible to tens of thousands of fungal species, whereas only a few hundred types of fungi can harm humans and other mammals.

Answer:

.0388 atm

Explanation:

Since temperature is not given , we assume that it is constant . So we can apply Boyle's law . According to it

P₁ V₁ = P₂ V₂

P₁ and V₁ are pressure and temperature initially and P₂ and V₂ are pressure and volume finally .

Putting the given values

.12 x 2.31 = 7.14 x P₂

P₂  = .12 x 2.31 / 7.14

= .0388 atm .