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19. place moth balls in the closet and observe after several days.

20. whenever wax or a candle burns it turns from solid to liquid but again at room temperature it turns to solid

21. evaporation, condensation, precipitation

22. it produces new substances

23. vinegar Bubbles when baking soda is added

24. steam

Answer:

The kinetic energy of the electron just before the collision is 9.3 eV.

Explanation:

We can find the kinetic energy of the electron before the collision can be found by energy conservation:

[tex] E_{i} = E_{f} [/tex]

[tex] K_{a_{i}} + K_{e_{i}} = K_{a_{f}} + K_{e_{f}} [/tex]   (1)

Where:

[tex]K_{a_{i}}[/tex]: is the initial kinetic energy of the atom

[tex]K_{a_{f}}[/tex]: is the final kinetic energy of the atom = 6.1 eV + [tex]K_{a_{i}}[/tex]

[tex]K_{e_{i}}[/tex]: is the initial kinetic energy of the electron =?

[tex]K_{e_{f}}[/tex]: is the final kinetic energy of the electron = 3.2 eV

By solving equation (1) for [tex]K_{e_{i}}[/tex] we have:

[tex]K_{a_{i}} + K_{e_{i}} = (6.1 eV + K_{a_{i}}) + 3.2 eV[/tex]

[tex] K_{e_{i}} = 6.1 eV + 3.2 eV = 9.3 eV [/tex]

Therefore, the kinetic energy of the electron just before the collision is 9.3 eV.

I hope it helps you!

Answer:

the moving of something form it's places or position

Answer:

Amount of oxygen needed is 5,000 liter

Explanation:

Given:

Percent of air in oxygen = 1%

Find:

Oxygen if 50 liter of wind

Computation:

Oxygen if 50 liter of wind  = 50 liter wind[100% / 1% ]

Oxygen if 50 liter of wind  = 50 liter wind[100]

Oxygen if 50 liter of wind  = 50[100]

Oxygen if 50 liter of wind  = 5,000

So,

Amount of oxygen needed is 5,000 liter

Answer:

O A. AB + CD + AC + BD

explanation:

Explanation:

A.ab+cd+ac+bd is your answer

Answer:

Explanation:

Lead Monoxide: PbO

Nitric Acid: HNO3

PbO + 2 HNO3 ---> Pb(NO3)2 + H2O

Answer:

Explanation:

mono mean single so lead monoxide is PbO

nitric acid is HNO3

both Pb n O are double-charged while H n NO3 are single

so balanced eqn is:

PbO + 2HNO3 -> Pb(NO3)2 + H2O

Answer: The mass density is 1166.36 [tex]kg/m^{3}[/tex].

Explanation:

Given: Weight of sample in air [tex](F_{air})[/tex] = 500 N

Weight of sample in alcohol [tex](F_{alc})[/tex] = 200 N

Specific gravity = 0.7 = [tex]0.7 \times 1000 = 700 kg/m^{3}[/tex]

Formula used to calculate Buoyant force is as follows.

[tex]F_{B} = F_{air} - F_{alc}\\= 500 - 200 \\= 300 N[/tex]

Hence, volume of the material is calculated as follows.

[tex]V = \frac{F_{B}}{\rho \times g}[/tex]

where,

[tex]F_{B}[/tex] = Buoyant force

[tex]\rho[/tex] = specific gravity

g = acceleration due to gravity = 9.81

Substitute the values into above formula.

[tex]V = \frac{F_{B}}{\rho \times g}\\= \frac{300}{700 \times 9.81}\\= \frac{300}{6867}\\= 0.0437 m^{3}[/tex]

Now, mass of the material is calculated as follows.

[tex]mass = \frac{F_{air}}{g}\\= \frac{500 N}{9.81}\\= 50.97 kg[/tex]

Therefore, density of the material or mass density is as follows.

[tex]Density = \frac{mass}{volume}\\= \frac{50.97 kg}{0.0437 m^{3}}\\= 1166.36 kg/m^{3}[/tex]

Thus, we can conclude that the mass density is 1166.36 [tex]kg/m^{3}[/tex].

Answer:

In both voltaic and electrolytic cells, oxidation occurs at the anode, while reduction occurs at the cathode. Thus, both these cells exhibit redox reactions. In both these cells, electrons flow from the anode to the cathode through the externally connected conductor.

Answer:

ELECTROLYTIC CELL

An electrochemical cell in which a non-spontaneous chemical reaction takes place when electric current is passed through the solution,is called an electrolytic cell.

EXAMPLE

Nelsons cell and Downs cell

VOLTAIC CELL OR GALVANIC CELL

The electrochemical cell in which a spontaneous chemical reaction takes place and generates electric current is called galvanic and voltaic cell.

EXAMPLE

Daniel cell

Explanation:

Answer:

option B is the correct answer

Answer: Decomposition is the answer

Explanation: why because aluminium hydroxide would decomposes in the presence of heat and would form an oxide which is aluminium oxide and would also form water as a product.

HOPE THIS HELPS!!

Answer:

Explanation:

If a substance contains ionic bonds, then it’s properties would include high melting and boiling points, a crystalline structure, the ability to dissolve quite easily in water, the ability to conduct electricity, have good insulation and lastly be quite hard and brittle.

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Answer:

27.9 g

Explanation:

CsF + XeF₆ → CsXeF₇

First we convert 73.1 g of cesium xenon heptafluoride (CsXeF₇) into moles, using its molar mass:

As 1 mol of cesium fluoride (CsF) produces 1 mol of CsXeF₇, in order to produce 0.184 moles of CsXeF₇ we would need 0.184 moles of CsF.

Now we convert 0.184 moles of CsF to moles, using the molar mass of CsF:

Answer: The statement diffusion occurs when particles spread from areas where they are less concentrated to areas where they are more concentrated, is false.

Explanation:

When particles or atoms of a substance are able to move rapidly from one place to another then it is called diffusion.

During diffusion, particles tend to move apart from each other.

For example, spreading of dye molecules into water.

Thus, we can conclude that the statement diffusion occurs when particles spread from areas where they are less concentrated to areas where they are more concentrated, is false.

Answer:

2.2 × 10⁻³ mol

Explanation:

Step 1: Calculate the number of equivalents in 0.50 L of blood

The blood calcium level of 8.8 meq/L.

0.50 L Blood × 8.8 meq/L = 4.4 meq = 4.4 × 10⁻³ eq

Step 2: Calculate the number of moles of calcium

Calcium has a charge of 2. Thus, it has 2 equivalents per mole.

4.4 × 10⁻³ eq × 1 mol/2 eq = 2.2 × 10⁻³ mol

Answer: The heat energy produced is 53831.25KJ

Explanation:

METHANE is the main component of natural gas. It can undergo combustion reaction in air with a bright blue flame to produce carbondioxide and water. The heat of reaction (enthalpy) is negative because heat is absorbed during the chemical reaction. To calculate the heat energy produced by the combustion of one kilogram (1 kg) of methane the following steps are taken:

Molecular mass of methane =16 gm/mol.

So moles of 1 kg methane =

Given mass of methane ÷ molecular weight of methane

But the given mass = 1kg = 1000g

Therefore,

moles of 1000g methane = 1000÷16

= 62.5 moles

Hence, energy evolved = (moles of methane) × (heat of combustion)

Therefore,

heat energy produced= 62.5 × (-861.3kj)

= -53831.25kj

​

The heat energy produced by the combustion of one kilogram of methane is –53831.25 KJ

We'll begin by calculating the number of mole in 1 Kg of CH₄

Mass of CH₄ = 1 kg = 1000 g

Molar mass of CH₄ = 12 + (4×1) = 16 g/mol

Mole = mass /molar mass

Mole of CH₄ = 1000 / 16

CH₄ + 2O₂ —> CO₂ + 2H₂O ΔH = –861.3 KJ

From the balanced equation above,

1 mole of CH₄ reacted to produce –861.3 KJ.

Therefore,

62.5 moles of CH₄ will react to produce = 62.5 × –861.3 = –53831.25 KJ

Thus, –53831.25 KJ of heat energy is produced.

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Answer:

it is option (d)

it has more mass than any of the other planets of the inner solar system

Answer:

Inference

Explanation:

I mean, it's not difficult.

A theory is an unproven explanation.

An inference is a guess/educated guess where you don't have all the facts.

For example, if "Bob" is caught in the kitchen with a ketchup stain on his shirt, you are inferencing that he used the ketchup.

However, if you see a ketchup bottle nearby or saw it earlier, then it is not, because you already have the facts that ketchup was used.

Answer:

The balanced equation would be:

3AgNO3+Al→3Ag+Al(NO3)3

Explanation:

Answer:

Mendel, Inheritance/Heredity

Explanation:

Gregor Mendel (1822-1884) was an Austrian monk and scientist as stated in this question. He is referred to as the FATHER OF GENETICS due to his immense contributions to the principle of inheritance.

Gregor Mendel via his several works conducted on pea plants was able to demonstrate how traits passed down from parents to offsprings in a process called INHERITANCE OR HEREDITY.

Your Answer is : 1st Mendel  and 2nd heredity.

Explanation:

Answer:

C = m/V

Explanation:

In order to calculate the concentration of a mixture you would need to use the formula for concentration, which is the following...

C = m/V

In this formula C is the concentration, m is the mass of the compound that is being added and mixed into the solution, and V is the total volume of the mixture. The mass of m is in terms of number of moles. Therefore, we would need more information in order to calculate the actual concentration of the mixture that you are trying to find in this scenario. Using the formula above should be enough using the values that you have in your actual workbook.

Answer:

The conditions for the formation of an electrovalent bond are as follows: The atom which changes into cation (+ ive ion) should possess 1,2 or 3 valency electrons. It will loose these electrons to form cation with +1,+2 or +3 charge

Answer:

Explanation:The equation for this is F = -GmM/R^2 where the minus sign says the force is attractive m is 10 kg, M is 20 kg and R is 5 meters. If you crunch the numbers you get an answer of:

Answer:

P2 = 900 mmHg.

Explanation:

Given the following data;

Initial pressure = 450 mmHg

Initial temperature = 100°C

Final temperature = 200°C

To find the final pressure, we would use Gay Lussac's law;

Gay Lussac states that when the volume of an ideal gas is kept constant, the pressure of the gas is directly proportional to the absolute temperature of the gas.

Mathematically, Gay Lussac's law is given by;

[tex] PT = K[/tex]

[tex] \frac{P1}{T1} = \frac{P2}{T2}[/tex]

Making P2 as the subject formula, we have;

[tex] P_{2}= \frac{P1}{T1} * T_{2}[/tex]

[tex] P_{2}= \frac{450}{100} * 200 [/tex]

[tex] P_{2}= 4.5 * 200 [/tex]

Final pressure, P2 = 900 mmHg.

Answer:

Increased surface area - finely divided solute

like dissolves like - matching polarity

temperature - rate proportional to kinetic energy

stirring spreads - solute throughout solution

Answer:

For 1: 6.68 g of nitrogen dioxide will contain [tex]8.73\times 10^{22}[/tex] number of molecules

For 2: The given amount of nitrogen dioxide molecules has a mass of 41.31 g.

Explanation:

According to the mole concept:

1 mole of a compound contains [tex]6.022\times 10^{23}[/tex] number of molecules

The number of moles is defined as the ratio of the mass of a substance to its molar mass. The equation used is:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(1)

We are given:

Mass of nitrogen dioxide = 6.68 g

Molar mass of nitrogen dioxide = 46 g/mol

Putting values in equation 1, we get:

[tex]\text{Moles of nitrogen dioxide}=\frac{6.68g}{46g/mol}=0.145mol[/tex]

Using above concept:

If 1 mole of a compound contains [tex]6.022\times 10^{23}[/tex] number of molecules

So, 0.145 moles of nitrogen dioxide will contain = [tex](0.145\times 6.022\times 10^{23})=8.73\times 10^{22}[/tex] number of molecules

Hence, 6.68 g of nitrogen dioxide will contain [tex]8.73\times 10^{22}[/tex] number of molecules

We are given:

Molecules of nitrogen dioxide = [tex]5.41\times 10^{22}[/tex] molecules

Using the above concept:

If [tex]6.022\times 10^{23}[/tex] number of molecules are present in 1 mole of a compound

So, [tex]5.41\times 10^{22}[/tex] number of molecules will be present in = [tex]\frac{1mol}{6.022\times 10^{23}}\times 5.41\times 10^{22}=0.898[/tex] moles of nitrogen dioxide

We know, molar mass of nitrogen dioxide = 46 g/mol

Using equation 1:

[tex]0.898mol=\frac{\text{Mass of nitrogen dioxide}}{46g/mol}\\\\\text{Mass of nitrogen dioxide}=0.898mol\times 46g/mol=41.31g[/tex]

Hence, the given amount of nitrogen dioxide molecules has a mass of 41.31 g.

Cu(s) + Ni(NO3)2(aq) ⇒Ni(s) + Cu(NO3)2(aq)

The answer is option B.

Electrochemical or hobby series when the electrodes (metals and non-metals) in touch with their ions are organized on the idea of the values of their preferred discount potentials or standard oxidation potentials, the resulting series is called the electrochemical.

The electrochemical series is built up by means of arranging various redox equilibria so as of their fashionable electrode potentials (redox potentials). The maximum poor E° values are placed at the pinnacle of the electrochemical series, and the maximum wonderful at the lowest.

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Answer:

hydronium and hydroxide ions are present both in pure water and in all aqueous solutions, and their concentrations are inversely proportional as determined by the ion product of water (Kw). The concentrations of these ions in a solution are often critical determinants of the solution’s properties and the chemical behaviors of its other solutes, and specific vocabulary has been developed to describe these concentrations in relative terms. A solution is neutral if it contains equal concentrations of hydronium and hydroxide ions; acidic if it contains a greater concentration of hydronium ions than hydroxide ions; and basic if it contains a lesser concentration of hydronium ions than hydroxide ions.

Answer:

hydronium and hydroxide ions are present both in pure water and in all aqueous solutions, and their concentrations are inversely proportional as determined by the ion product of water

Explanation:

Not my work! I hope this helps!  

Answer: so in this question are reactants are calcium hydroxide and ammonium chloride

Explanation: first of all know that a salt would be formed so here the salts present are calcium and chloride so they would react to form the salt calcium chloride, then since ammonium ions are present ammonia gas would be formed then, hydroxide ions (OH) are also present so water would be formed so our final products would be calcium chloride , ammonia and water .

WORD EQUATION

calcium hydroxide+ ammonium chloride⇒ calcium chloride+ ammonia+ water

CHEMICAL EQUATION

CA(OH)2+2NH4CL⇒ CACL2+2NH3+2H2O