True or false The density of a subsidence is always the same

Answer:

after burning the coal,0.8of coal was lost to produce Ash and it remained little amount of coal

The Independent variable  in the experiment is the type of covering material.

An experiment is the only way by which we are able to decode cause and effect relationships. Since science is empirical, every tentative explanation if a phenomenon is subjected to controlled tests. These controlled tests are what we call an experiment. There must be an independent variable and there must be  dependent variable. The independent variable is the variable that is manipulated in the experiment while the dependent variable is the variable that changes as we manipulate the independendent variable.

Now, if we look at the experiment, we can see that we are manipulating the type of covering in order to determine the impact that it has on the time that it taking for cooling to occur.

Hence the Independent variable  in the experiment is the type of covering material. The type of the covering was being changed and then the impact of the change of the covering material on the cooling time is studied.

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Answer:

First look up the ideal gas law: PV=NRT, where P=pressure, V=volume, N=amount of gas in moles, R=universal gas constant, and T=Temperature in degrees K. See Ideal gas law - Wikipedia for details.

Then consider the following:

Inside a tire, V and R are constants, while P, N, and T vary.

What makes a tire seem hard or soft is the difference in pressure between the air in the tire and the air around the tire.

A so-called flat tire is not devoid of air; it just has the same pressure inside as outside.

When you pump up a tire, you are increasing N by forcing more air molecules into the tire. As V is a constant volume, you create a pressure difference between inside and outside.

This pressure difference varies with how much you pump the tire (P), as well as the temperature around the tire (T) and the air pressure around the tire (atmospheric or “ambient” pressure).

The fact that an inflated tire is in balance with ambient pressure — with the added influence of PV=NRT — has some counter-intuitive results. For example,

I’ve had bike tires blow out by being left in a hot car. Why? The pressure in the car is the same, but the pressure in the tire increases as T increases until it’s beyond the safe limit.

More rarely, I’ve heard reports of bike tires blowing out by being carried in the unpressurized hold of an airplane. In this case, the tire doesn’t get hot; instead, the pressure outside the tire decreases, until the tire can’t hold in the pressure. In actuality, this is really hard to do; the tire has to be over-pressurized to start with; the difference in ambient pressure is not enough to blow out a typical bike tire.

16.254 × [tex]10^{23}[/tex] molecules

The formula for sulfur dioxide is [tex]SO_2[/tex].

MOLECULES of sulfur dioxide are present in 2.70 moles of this compound

so, we have given the moles of [tex]SO_2[/tex] = 2.70 moles

we have find the number of molecules = ?

1 mole of Na = 6.022×[tex]10^{23}[/tex] molecules

so 2.70 moles of SO2 contains = 2.70[tex]\times[/tex] 6.022×[tex]10^{23}[/tex] molecules

moles of SO2 contains = 16.254 × [tex]10^{23}[/tex] molecules

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Considering the image, sample A bears the lowest value of Temperature change,

This is further explained below.

Generally, When there is a rise or decrease in temperature as a result of the transfer of heat, this is referred to as a temperature change.

This causes a change in the chemical equilibria toward the products or the reactants, which may be identified by examining the reaction and determining whether or not it is endothermic or exothermic.

In conclusion, Taking into consideration the picture, sample A has the lowest value of temperature change; this indicates that it will take the most time to cool down or change the temperature while it is being cooled down.

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Answer:

Oxygen gains two electrons to have an octet. The ionic bond between ions results from the electrostatic attraction of opposite charges. The final formula of magnesium oxide is MgO.

Explanation:

Answer:

a pebbles density is 34 meters and has a volume of 2

Alteration in Temperature, Color Change Noticable Odor, Developing a Precipitate and The emergence of bubbles are the factors  indicates that the gases are chemically reacting.

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a substance that is  made of two oxygen atoms for each carbon atom .

A compound is the  substance that contains two or more atoms which chemically combined together in a fixed ratio by mass

.For example, CO₂ is a compound and its ratio by mass is 12:32 which is equal to 3:8. Whereas when a substance with atoms of only a single element is known as a pure substance.

So, we can conclude that the substance made of two oxygen atoms for each carbon atom describes a compound.

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Answer:

125

Explanation:

the positive 2 on the exponent means you have to move the decimal point 2 times to the right, giving you 125.

you can also simplify the expression to 1.25 * 100 and get 125

Possible identity of this metal sample is gold

Here given data is unknown metal mass=14.8 g sample displaces=0.767 mL of water we have to find density of given metal=?

Density=mass/volume

Here mass=14.8 g and volume=0.767

Density=mass/volume

Density=14.8g/0.767

= 19.29≈19.30 means 19.3

So in the listed metal above answer are matched with gold

Therefore gold has  19.3 density.

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2 is the region where the substance is in both solid and liquid phases.

The term "phase" refers to a uniform or homogeneous quantity of matter that may be mechanically separated from a nonhomogeneous mixture. It can be made up of a single material or a combination of substances. Although crystalline, colloid, glassy, amorphous, and plasma phases are thought to exist, the three basic phases of matter are solid, liquid, and gas.

A phase change is defined as the transformation of a phase from one form to another. A system can have phases that are solid, liquid, or gaseous. Strong atomic bonds and high viscosity give solids their characteristic rigid form. Insofar as they have a three-dimensional periodic atomic arrangement, most solids are crystalline; nevertheless, certain materials lack this periodic organization and are noncrystalline, or amorphous.

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Answer:

Solid and lipid element

A block has a side length of 2.0 cm x 5.6 cm x 11.4 cm

he block has a density of 8.5 g/cm³.

block's mass = ?

from above statement we have got volume = 2.0 * 5.6 * 11.4

                                                                       = 127.68cm³

density = 8.5 g/cm³.

now density = mass / volume

mass = density * volume

mass = 1,085.28 g

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Conversion of units is the conversion between different units of measurement for the same quantity and the values is the same as 400.0 mm is 4.0 x 10³ cm

Here given value are 400.0 mm and the value are in millimeter we have to convert mm into cm so 1 millimeter = 0.1 centimetre

Here given value are 400.0 mm in that only decimal point correction are seen means here three zeros are seen then we will write this zeros in 10 raised to power then correct option is c means 4.0 x 10³ cm

400.0 mm×1cm/10³ = 4.0 x 10³ cm

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Octane is a hydrocarbon and an alkane with the chemical method C8H18, and the condensed structural system CH3CH26CH3. Octane has many structural isomers that fluctuate by using the quantity and vicinity of branching inside the carbon chain. any such isomers, 2,2,four-trimethylpentane usually called iso-octane is used as one among the standard values in the octane score scale.

Octane is colloquially used as a quick form of octane score specifically in the expression high octane. Octane score is an index of a gasoline's ability to withstand engine knock-in engines having exclusive compression ratios, which is a feature of octane's branched-chain isomers, especially iso-octane. The octane rating of gas is not directly related to the strength output of an engine. using gasoline of a better octane than an engine is designed for can't boom electricity output.

Nonane can have a better boiling factor than octane because it has an extended carbon chain than octane. Octane can have a higher boiling point than 2,2, three,three‑tetramethyl butane, because it branches much less than 2,2,3,3‑tetramethyl butane, and consequently has a larger floor vicinity and extra van der Waals forces. Nonane could have a better boiling factor than octane because it has an extended carbon chain than octane.

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The brass is neither an element nor a compound but it can be a mixture.

Brass is an alloy of copper and zinc. It can be used achieve mechanical, electrical and chemical properties.

We can say that from the definition the brass is neither element nor the compound but it can be a mixture. Brass is a homogenous mixture of the metals Copper and zinc. The common percentage of the brass is 65% of cooper and 35% of zinc.

Brass is used for preventing the corrosion and also used for providing low friction. The brass is commonly used in locks, zippers, plumbing, electrical plugs and in sockets. The used of the brass is not widely range but it is commonly used for the decorating purposes.

So we can conclude that the brass is neither an element nor a compound but it can be a mixture.

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While sea water does not freeze at -1°C, fresh water does.

The prediction will be "I think that the salt in the seawater keeps it from freezing at -1 Celcius."

The problem statement is "How come the water on the roof is frozen and the sea water is not?"

The statement that contains data is "I'm going to get some fresh water and some salt water and expose them to a temperature of-1°C and see what happens."

In a temperature of -1°C, fresh water is frozen while sea water is not.

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The wavelength of the light is obtained as 122nm.

From the Bohr model of the atom, we know that an electron could absorb energy and move from a lower to a higher energy level. When this electron returns to its ground state, energy is emitted in the form of a photon of visible light.

Given that;

1/λ = RH (1/n1^2 - 1/n2^2)

λ = wavelength of the light

n1 = final level

n2 = initial level

1/λ = 1.097 * 10^7(1/1^2 - 1/2^2)

1/λ =  1.097 * 10^7(1 - 0.25)

λ = 1.22 * 10^-7 m or 122nm

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The temperature of the can reduces and it turns into ice and the thermal energy is exchanged between the walls.

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These rocks turns into the rust by the process of the oxidation. As rust can be expands, so it can weakens the rocks and helps break it apart.

We know that from our daily life rust for example is iron oxide. When specially the rocks which contains the iron, if exposed or leave to the water and air, then the iron undergoes an oxidation reaction as a result which can weaken the rocks and make the rocks crumble from the inside.

Actually the oxidation produces an iron oxides minerals. The process of the rusting can also change the colour of the iron. It can be changed in several colours like red, brown or yellow.

So we can conclude that these rocks turns into the rust by the process of the oxidation. As rust can be expands, so it can weakens the rocks and helps break it apart.

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The correct answer is 48.36 g .

A mole of any material is equal to 6.023 x 1023, or Avogadro's number. Additionally, it is employed to express concentrations in terms of moles per litre or molecular weight.

Number of moles of O = (Mass of O / Molar mass of O) = ( 25.7 g / 15.999 g/mol) = 1.6 mol

3 mol of O combine with 2 mol of Fe (iron) to form Fe​​​​​2​​​O3 . Or, 1 mol of O combines with (2/3) mol of Fe.

Therefore, 1.6 mol of O combine with = (2/3) × 1.3 =  0.866 mol of Fe

Mass of Fe (iron) = (Number of moles of Fe) × (Molar mass of Fe) = (0.866 mol) × (55.845 g/mol) = 48.36 g

Hence, the amount of iron required = 48.36 g

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Answer:

The energy of one photon is given by the expression, E=hν

where, h=6.626×10

−34

Js and ν=5×10

14

s

−1

E=6.626×10

−34

×5×10

14

=3.313×10

−19

J

Explanation:

The number of moles of KBr present in 150 mL of a 0.122 M solution is 0.0183mol.

The number of moles in a solution can be calculated by multiplying the molarity of the solution by the volume as follows:

no of moles = molarity × volume

Molarity is the concentration of a substance in solution, expressed as the number moles of solute per litre of solution. It is the most common way to express the concentration of a solution.

According to this question, there are 150 mL of a 0.122 M pottasium bromide (KBr) solution, the number of moles in this solution can be calculated as follows;

no of moles = 150mL/1000 × 0.122M

no of moles = 0.0183mol

Therefore, the number of moles of KBr present in 150 mL of a 0.122 M solution is 0.0183moles.

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the correct option is c = 12 electrons.

There are fours quantum numbers

1) Principal Quantum Number (n)

2) Azimuthal Quantum Number (L)

3) Magnetic Quantum Number (ml)

using the above information ,

4) If n= 1

L = N-1

L = 1-1 =0

'0' represent the S orbital.

each orbital can hold hold only two electrons.

The number of orbital is = 1S

4) If n= 2

L = n-1

L = 2-1

L = 1

m = -L , 0 , +L

M = +1 , 0 , -1

The number of orbitals is = 1s , 2s and 2p (Only two orbitals.)

each orbital can have only two electrons , S orbital contains two electrons and 2p (2px, 2py,2pz)= 6 electrons.

5) If n=3

L= n-1

L = 3-1= 2

L = 0,1,2

number of orbitals = S, P,D

m = -2,-,1,0,1,2

The number of orbitals are = 1S ,2S,2p, 3p ,4d

3p contains the electrons = 6 electrons.

So the number of electrons contains in p orbital from n=1 to n= 3 is 0+6+6= 12 electrons.

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The mass of the CO2 28.4 Kg.

The term combustion refers to burning. When a material is combusted, the material is made to burn in oxygen. This in itself is an oxidation reaction. It is common that we have to burn the alkanes and some other kinds of hydrocarbons for the process of obtaining energy.

In this case, we can see that the substance that we have to  burn is pentane. The reaction equation is written in the manner; C5H12+8O2→6H2O+5CO2.

Number of moles of pentane = 9.28 * 10^3 g/ 72 g/mol

= 128.9 moles

Now;

If 1 mole of pentane produces 5 mols of CO2

128.9 moles of pentane would produce 128.9 moles *  5 mols/ 1 mole

= 644.5 moles of CO2

Mass of CO2 produced = 644.5 moles of CO2 * 44 g/mol = 28.4 Kg

Hence, we have about 28.4 Kg of CO2 produced

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