What did people use for energy before fossil fuel and electrical power energy was harnessed?
They used whale oil and steam power to run machines.
Humans had only their own muscles and a knowledge of levers and pulleys for power.
Humans burned wood to power their machines.
Humans used muscle power and direct wind and water power.

The Final Pressure of the gas is 6 kPa

At constant Temperature , the absolute pressure exerted by the gas is inversely proportional to the volume of the gas.

[tex]\rm P_1V_1 = P_2V_2[/tex]

It is given that

[tex]\rm P_1 = 300k.Pa\\T_1 = 25 \; Degree\\V_1 = 2L\\V_2 = 100L\\T_2 = 25 Degree\\P_2 = ?[/tex]

To determine Final Pressure , Boyle's Law will be applied

300 * 2 = P₂ * 100

P₂ = 300 * 2 / 100

P₂ =6 kPa

Therefore the Final Pressure of the gas is 6 kPa.

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Answer:D

Explanation:

A single-replacement reaction occurs when one element replace another in a single compound.

B. One reactant replaces an element in another reactant.

Chemical reactions occur when reactants bond or break apart to form new substances known as the products.

Types of Reactions

There are a few main types of reactions:

All of these are different ways chemical reactions can occur.

Synthesis

Synthesis occurs when two different reactants form one product. This would be a match for answer choice A.

Decomposition

Decomposition occurs when one reactant breaks down, usually through heat, to form 2 different products, which matches answer choice D.

Single Replacement

Single replacement occurs when there are 2 reactants, a substance and an element, and the singular elements replaces one of the elements in the substance to form new products. Since this matches answer choice B, this is the correct answer.

Double Replacement

Finally, double replacement is when there are 2 reactants and each switches an element with the other. This is seen in answer choice C.

For this example remember that [tex]NO_{3}[/tex] is a polyatomic ion and acts as a singular element.

Answer:

ionic bond

Explanation:

Answer:

Ionic bonding

Explanation:

Salt    Na+Cl-       is an example

Answer:

31536000

Explanation:

There are 31536000 seconds in a day.

60s x 60min x 24hrs x 365 days = 31536000sec

Heating up a reaction increases the speed of a reaction until the enzyme denatures.

Enzyme denaturation occurs when a biological protein catalyst does not work anymore due to a high temperature that alters its tridimensional conformation.

This cellular process (denaturation) is well known to be one of the main causes of enzymatic failure.

In conclusion, heating up a reaction increases the speed of a reaction until the enzyme denatures.

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Answer:

a solution: for example when sugar is dissolved in water it becomes a sugar solution

The partial pressure of xenon is 571.5 KPa if the total pressure is 1436.4kPa.

The pressure exerted by a (specified) component in a mixture of gases.

According to Dalton's law of partial pressure, the net pressure of a gaseous mixture is always equal to the sum of the partial pressures of individual gases.

Now we are given that the total pressure is 1436.4kPa

The partial pressure of helium is 348.1kPa

The partial pressure of oxygen is 516.8kPa

Partial Pressure of xenon?

Using dalton's law;

1436.4kPa = 348.1kPa + 516.8kPa + partial pressure of xenon

The partial pressure of xenon is 571.5 KPa.

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Answer:

Adding sugar to water will raise the boiling point and decrease the freezing point of water.

Explanation:

Hope this helps!

If same amount of sugar  added  to the same amount of water and boiled it then boiling point increases.

When sugar added to water it become solution.

Example: If water boils at 100°C then solution with 80%  sugar in 20% of water boils at 112°C.

Since, sugar is non-volatile solute. So, when we boil the solution of sugar in water then water boils easily in low temperature but more  high temperature is required to boil sugar.

The solute which has higher vapor pressure as compare to solution in which it dissolve is called non-volatile solute.

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Any deviation in the image of an object when light passing from one medium to other is assciated to the phenomenon of refraction.

It is the deflection from a straight path undergone by a light ray while passing from one medium (such as air) into another (such as glass) in which its velocity is different.

Basically, the light refraction gives the pencil a slight magnifying effect, which makes the angle appear bigger than it actually is, causing the pencil to look crooked.

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Answer:

Explanation:

Any deviation in the image of an object when light passing from one medium to other is assciated to the phenomenon of refraction.

What is refraction ?

It is the deflection from a straight path undergone by a light ray while passing from one medium (such as air) into another (such as glass) in which its velocity is different.

Basically, the light refraction gives the pencil a slight magnifying effect, which makes the angle appear bigger than it actually is, causing the pencil to look crooked.

After Looking at the pencil from the side of a clear glass or resealable plastic bag filled three-fourths with water, we will see the light bends around the pencil, causing it to look bent in the water.

When the pencil tilt from side to side, It looks so dramatically broken on looking at it from different angles.

We can magically “fix” the broken pencil by changing where the pencil is positioned in the glass.

The number of moles of oxygen required to completely react with 54 g of aluminum is 1.5 moles.

moles = reacting mass/molar mass

moles = 54/27

moles = 2 moles

From the given reaction of oxygen and aluminum;

4Al +  30₂   →   2Al₂O₃

4 moles of Al ----------> 3 moles of oxygen

2 moles of AL --------> ? moles of oxygen

= (2 x 3)/4

=  1.5 moles

Thus, the number of moles of oxygen required to completely react with 54 g of aluminum is 1.5 moles.

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The temperature is always the same.

Assume we have something in solid phase. As we increase the temperature, the particles on the solid increase their kinetic energy, thus, the particles move more.

This causes that the volume of the object increases (for example when we heat up a metal and it dilates) and this keeps happening until we reach a critical point, when we are near a change of phase.

At this point the energy given is not used to increase the temperature of the object, but is used to "break" bonds in such a way that the particles are more free than before.

When all these bonds are "broken" the change of phase is completed, and in the case of the solid, we go from solid phase to liquid phase.

So, the temperature is always the same at the beginning of a change of state compare with the temperature at the end of the change

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Answer:

empirical formula is the simplest formula of a compound with 4.433g phosphorus and 5.717g ooxygen.

Railroad tracks built with a flexible expansion and contraction joint because the tracks have a larger coefficient of linear expansion than the ground beneath. Hence, Correct opotion is option (A)

The linear expansion of a solid under a change in temperature can be measured using Δℓ/ℓ = αΔT and has applications in the ways solids expand and contract in everyday life.

The strain that the object undergoes has implications in engineering when fitting objects among each other.

Hence, Railroad tracks built with a flexible expansion and contraction joint because the tracks have a larger coefficient of linear expansion than the ground beneath. Therefore, Correct opotion is option (A)

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The statement "According to Le Châtelier's principle, an increase in temperature will shift the equilibrium position toward the products in an endothermic reaction" is definitely true.

Le Châtelier's principle may be defined as transformations in the temperature, pressure, volume, or concentration of a system that will lead to observable and conflicting changes in the strategy in order to accomplish a refreshed equilibrium state.

According to Le Châtelier's principle, an increase in temperature generates the equilibrium to move in the direction of the product of the endothermic reaction, and the decrease in the temperature rationales the equilibrium to move in the direction of the product of the exothermic reaction.

Therefore, it is well described above.

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The primary distinction between the digestive systems of cows and humans is that the former uses a foregut fermenter while the latter uses a straightforward monogastric digestion. The types of teeth, mouths, stomachs, guts, and digestive enzymes released by the gut also vary between the two digestive systems. Cows and humans have different digestive systems because they have evolved two different sorts of dietary patterns based on their capacities. The primary distinctions between the digestive systems of cows and humans are in the types of teeth, mouths, stomachs, and intestines, as well as the enzymes released.

Answer:

The main difference between cow and human digestive system is that cow exhibits a foregut fermenter digestion whereas human exhibits a simple monogastric digestion. Both digestive systems also differ by the type of teeth, mouth, stomach, gut, and digestive enzymes secreted by the gut.

Explanation:

The molar volume of a gas at standard temperature and pressure is 22.4L

Because the particles in gases are compressible, they can be driven to enclose one another when subjected to high pressure. As a result, the volume of the gas is smaller and there is less free space. The temperature has an impact on gas volume as well. A gas expands as a result of its molecules moving more quickly when it is heated. The comparison of gas volumes must be done at standard temperature and pressure due to the variation in gas volume caused by variations in pressure and temperature. The definition of standard temperature and pressure (STP) is (273.15K) and 1atm pressure. The volume of one mole of a gas at STP is its molar volume. A mole (6.02 x 10^23 typical particles) of any gas takes up 22.4L at STP.

using ideal gas law:-

PV =nRT

P = 1.00atm

n = 1.00 mol

R = 0.0821 L atm/mol  K

T = 273 K

V = ?

V = nRT/P

V = (1.00 x 0.081 x 273)/1.00

V = 22.4 L

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Answer:

12 seconds

Explanation:

Time taken by 50cm³ of oxygen to diffuse from pinhole

= 1 minute = 60 seconds

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[tex] \textsf{ Rate of oxygen} \sf (O_2) = \frac{50}{60} [/tex]

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Let time taken by 50cm³ of hydrogen to diffuse from pinhole = t seconds

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[tex] \textsf {Rate of hydrogen } \sf(H_2) = \frac{50}{t} [/tex]

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According to the formula

[tex] \sf \frac{Rate \: of \: hydrogen(H_2)}{Rate \: of \: oxygen(O_2) } = \sqrt{ \frac{Molar \: mass \: of \: O_2}{Molar \: mass \: of \: H_2} } [/tex]

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[tex] \large \sf \frac{50}{t} \div \frac{50}{60} = \sqrt{ \frac{\cancel{32}\small 16}{\cancel2} } \\ \\ \sf \large \frac{ \cancel{50}}{t} \times \frac{60}{ \cancel{50}} = \sqrt{16} \\ \\ \sf \large \frac{60}{t} = 4 \\ \\ \sf \large \frac{ \cancel{60} \: \small12}{ \cancel4} = t \\ \\ \large \underline{ \boxed{ \tt t = 12 \: seconds}}[/tex]

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Explanation:

There is an electrostatic force holding the electrovalent bonds together and they're usually structured, whereas in covalent, they are usually free and are only held together by a very weak intermolecular force

The Molar Concentration Of A =0.099 .

The Relative Molar Mass Of A = 35.0129 gm

Given,

Mass of HX = 3.5 g

Moles of solution B ([tex]Na_{2} CO_{3}[/tex]) = 0.05 moles

Volume of HX = 26.10 mL

Volume of Solution B = 25 mL

Molecular weight of solution B = 2(atomic weight of Na )+ atomic weight of C + 3(atomic weight of O)

                 = 2(23) + 12 + 3(16)

                 =106 gm

Equivalent weight of  [tex]Na_{2} CO_{3}[/tex] = molecular weight / 2 = 106 /2  =53 g

Mole = mass / molecular weight

∴0.05 = mass / 106

∴ mass = 5.3 gm [tex]Na_{2} CO_{3}[/tex]

Normality = mass ÷ (equivalent weight × volume of the solution in liter)

                = 5.3 ÷( 53 × 0.025)

                =4 N

So, by using formula ,

[tex]N_{1} V_{1} =N_{2} V_{2}[/tex]

[tex]N_{1}[/tex] = normality of solution B = 4 N

[tex]V_{1}[/tex] = volume of solution B = 25 mL

[tex]N_{2}[/tex] = normality of solution A = ? N

[tex]V_{2}[/tex] =Volume of solution A = 26.1 mL

∴ 4×25 = [tex]N_{2}[/tex] × 26.1

∴[tex]N_{2}[/tex] = 3.83 N

∴ normality of solution A = 3.83 N

from Formula of the normality we can find the equivalent weight of the A

Normality = mass of HX ÷ (equivalent weight × volume of the solution in liter)

3.83 = 3.5 ÷( equivalent weight × 0.0261)

∴equivalent weight = 35.0129 g

In case of HX the electron transfer is 1 ,so equivalent weight = molecular weight ; which is also termed as relative molar mass in given case.

∴The Relative Molar Mass Of A = 35.0129 g

Molar concentration = mass / molar mass

                               = 3.5 / 35.0129

                               = 0.099 mole

∴ The Molar Concentration of A  is 0.099 .

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[tex]\quad \huge \quad \quad \boxed{ \tt \:Answer }[/tex]

[tex]\qquad \tt \rightarrow \:36 \:\: g [/tex]

____________________________________

[tex] \large \tt Explanation \: : [/tex]

The given compound has 3 carbon atoms, so in 1 mole of that compound, there will be 3 moles of carbon atoms.

Mass of each mole of carbon atoms = 12 g

For 3 mole carbon atoms, it will be 12 × 3 = 36 grams

Answered by : ❝ AǫᴜᴀWɪᴢ ❞

Among the following options eating an energy bar by a hiker using a chemical potential energy.

Chemical potential energy is the energy stored in the chemical bonds of a substance.

The food we eat contains stored chemical energy.

As the bonds between the atoms in food loosen or break, a chemical reaction takes place, and new compounds are created.

The energy produced from this reaction keeps us warm, helps us move, and allows us to grow

Hence, eating an energy bar by a hiker using a chemical potential energy.

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Rutherford model task 1 is not supported by Thomson’s experimental evidence.

The atom consists of matter that may be split without releasing electrical charges.

It's also the smallest unit of matter with chemical element features. As a result, the atom is the fundamental unit of science.

The nuclear model of the atom was initially put out by Rutherford. His atomic model states that the majority of an atom's volume is empty,

The nucleus, which contains protons and neutrons, is located in the middle of the atom, and its electrons orbit the nucleus in well-defined paths.

If we discuss the research of some other scientists, like Dalton, Neil Bohr, and JJ Thomson, they are all mostly consistent with Rutherford's findings.

For instance, Dalton's atomic theory presupposed that all atoms are roughly the same size and that atoms interact to generate compounds.

According to Rutherford's theory, atoms have a fixed number of electrons that can be shared to create compounds.

The Bohr model, which posits that electrons orbit the nucleus in certain shells, is also consistent with Rutherford's findings, which gave rise to the idea of shells.

If we discuss Thomson's Plum Pudding Model, it describes atoms as negatively charged particles around a soup of positively charged ions. This is also consistent with Rutherford's findings, which show that positive nuclei are surrounded by negative electrons.

Although Rutherford's model was the greatest atomic model, it nevertheless drew on several earlier investigations and was therefore consistent with the outcomes of earlier models.

Hence rutherford model task 1 is not supported by Thomson’s experimental evidence.

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Answer:

I d K

Explanation:

First and fifth reaction shows endothermic reaction while the rest of it shows exothermic reaction.

The reaction between ammonium nitrate and water is an example of endothermic reaction because it absorbs heat from the surrounding environment.

Three drops of concentrated sulfuric acid added to 100 milliliters of water in a beaker makes the beaker hot because exothermic reaction occur.

Ammonium chloride dissolved in a beaker of water makes the beaker cold which shows that it is exothermic reaction because heat leaves the solution.

Uranium atoms are split to produce nuclear energy is an example of exothermic reaction.

Water separates into hydrogen and oxygen when an electric current is run through it that shows endothermic reaction.

Methane and oxygen are combined to produce methanol and heat is an example of exothermic reaction.

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Based on the calculations, the number of Si atoms in one unit cell is equal to 8 atoms/unit cell.

Mathematically, the volume of a unit cell can be calculated by using this formula:

V = a³

V = (543)³ × (1 × 10⁻¹²)³ × (100)³

Volume, V = 1.60 × 10⁻²² cm³.

Next, we would determine the mass:

Mass = density × volume

Mass = 2.33 × 1.60 × 10⁻²²

Mass = 3.73 × 10⁻²² grams.

Also, we would determine the mass of one silicon atom:

Mass = 28.09/(6.022 × 10²³)

Mass = 4.665 × 10⁻²³ g/atom.

Now, we can calculate the number of Si atoms in one unit cell:

Number = 3.73 × 10⁻²²/4.665 × 10⁻²³

Number = 8 atoms/unit cell.

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Answer:

Below

Explanation:

Units of specific heat are   J / (g- °C)

    so to get these units :

             1259 J / (25 g *6.1 °C) = 8.26  J / (g °C)

Depends on what kind of ions are present in the green solution

Explanation:

Cr3+, a famous green ion can obviously be displayed by a Cu2+ ion

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