Which change in oxidation number indicates oxidation? a) -i to +2 c) +2 to -3 b)ito -2 d) +3 to +2

1, 2, and 4, Two methods are used by astronomers to determine the age of the universe: 1) by searching for the earliest stars, and 2) by measuring the universe's rate of expansion and extrapolating back to the Big Bang.

Radiometric dating is the primary technique used by scientists to ascertain the age of the solar system and the planets. When certain heavier nuclei, such as those of plutonium and uranium, undergo radioactive decay, daughter nuclei of other, more stable elements are created.

The Hubble Time is the most basic way to calculate the age of the universe. We can see that light from far-off galaxies is Doppler Shifted towards redder wavelengths, indicating they are moving away from us. This is how we know the universe is expanding. The galaxy goes away more quickly the further away it is.

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The given question is incomplete. The complete question is:

How much heat is produced when 24.8 g of \(CH_4\) is burned in excess oxygen gas

Given: \(CH _4 +2O_2\rightarrow CO_2+2H_2O\)  ΔH= −802 kJ.

Answer: 1243.1 kJ

Explanation:

Heat of combustion is the amount of heat released on complete combustion of 1 mole of substance.

Given :

Amount of heat released on combustion of  1 mole of methane = 802 kJ kJ/mol

According to avogadro's law, 1 mole of every substance occupies 22.4 L at NTP, weighs equal to the molecular mass and contains avogadro's number \(6.023\times 10^{23}\) of particles.

1 mole of \(CH_4\) weighs = 16 g  

Thus we can say:  

16 g of \(CH_4\) on combustion releases heat = 802 kJ

Thus 24.8 g of \(CH_4\) on combustion releases =\(\frac{802}{16}\times 24.8=1243.1kJ\)

Thus heat released when 24.8 g of methane is burned in excess oxygen gas is 1243.1 kJ

Answer:

29.3

Explanation:

Answer: Silicon dioxide

Explanation:

di is 2 and since oxygen is 2

The given reaction is:A → B → C This problem is about finding the percentage yield of a reaction that starts with 0.131 mol of A and the actual yield of C is 4.98 g. To find the percentage yield, we will use the following formula:

Percentage Yield = (actual yield/theoretical yield) × 100%

The molar mass of C is 136.16 g/mo. We can use this to convert the actual yield of C from grams to moles. To do this, we will use the following formula:

Number of moles of C = Mass of C/molar mass of C

Number of moles of C = 4.98 g / 136.16 g/mol

Number of moles of C = 0.0366 mol

Now, let's find the theoretical yield of C:The balanced chemical equation for the reaction is:A → B → C

The stoichiometry of the reaction tells us that 1 mole of A gives 1 mole of C. Therefore, the theoretical yield of C is 0.131 mol.The percentage yield is:

Percentage Yield = (actual yield/theoretical yield) × 100%Percentage Yield = (0.0366/0.131) × 100%Percentage Yield = 27.9%

Therefore, the percentage yield of the reaction is 27.9%.

The percentage yield tells us how efficient a reaction is in producing the desired product. In this case, the reaction is only 27.9% efficient in producing C from A.

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The reaction for the given reaction is : A → C The reaction begins with 0.131 mol of A. Let the theoretical yield of C be y g. Therefore, the moles of C produced by the reaction are 0.131 mol. Since, the molar mass of C is 136.16 g/mol, therefore the theoretical yield of C can be calculated as: y = (0.131 mol) x (136.16 g/mol) = 17.82976 g Now, the actual yield of C is given to be 4.98 g.

Using the formula for calculating percentage yield, the percentage yield of C can be calculated as :Percentage yield of C = (Actual yield of C / Theoretical yield of C) x 100= (4.98 g / 17.82976 g) x 100 = 27.95 %Therefore, the percentage yield of C is 27.95 %.Note: The percentage yield of a reaction measures the efficiency of a reaction.

It represents the percentage of the theoretical yield that was actually obtained from the reaction. The percentage yield can never be more than 100 %.

Reactions that undergo shifts in their equilibrium must be... A. reversible reactions B. chemical reactions C. physical reactions D. nuclear reactions.

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Answer:

It is more active

Explanation:

This atom attracts all the elecrons of the atom forming energy levels in form of orbits

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The number of days must also be a whole number and the answer is 150.

Formula for calculating half-life is:t1/2 = ln2/λ

Where λ is the decay constant.

The decay constant (λ) of a radioactive isotope is 2.55 × 10−6s−1, what is its half-life (t1/2) in days?

The half-life of the isotope, we will use the formula:t1/2 = ln2/λ

Where:λ = 2.55 × 10−6 s−1

We can use the conversion factor to convert seconds to days:1 day = 86400 seconds

Therefore, the decay constant (λ) in days−1 is:

λ = 2.55 × 10−6 s−1 × (1 day/86400 s) = 0.000029514...day−1 (rounded to 9 decimal places).

Substituting into the formula:

t1/2 = ln2/λt1/2 = ln2/0.000029514...day−1t1/2 = 23,498.674... days (rounded to 3 decimal places).

Therefore, the half-life of the isotope is approximately 23,498.674 days.

To 3 significant figures, this is equal to 23,500 days.

Rounding up is recommended because half-life is a measure of the time required for half of the radioactive nuclei in a sample to undergo decay.

This is, of course, a discrete process, so the number of days must also be a whole number. The answer is 150.

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Answer:No

Explanation:

It doesn't make a chemical reaction if u do that. Hope that helps!❤

Answer:

its 210

Explanation:

Just add all atomic mass used in the formula together: 2*(14+16*3)+88= 2*62+88=124+88=210

Hope this was helpful

The relative formula mass of strontium nitrate Sr(NO₃)₂ is 210

The relative atomic masses of N, O and Sr are 14,16 and 88 respectively.

In calculating the relative atomic mass of an element with isotopes, the relative mass and proportion of each is taken into account. Adding the atomic masses together gives the relative formula mass of a compound

So, relative atomic mass of Sr(NO₃)₂ is calculated as

88+ 2(14+16×3) = 210

The atomic mass constant (symbol: mu) is defined as being 1/12 th of the mass of a carbon-12 atom. Since both quantities in the ratio are masses, the resulting value is dimensionless; hence the value is said to be relative atomic mass.

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Answer:

45

Explanation:

There are 12 Carbons

There are 22 Hydrogens

There are 11 Oxygens.

I think the answer is either 0 or 45. But the wording is very sloppy. It is not really atoms that are present. There are ions.

Go with 45 but hold your nose when writing your answer.

Answer:

0.00580 →

3000 →

0.000908 →

200. →

Explanation:

yay

Answer:

\(\large \boxed{\mathrm{view \ explanation}}\)

Explanation:

4.060 × 10⁵ (scientific notation)

The decimal point moves 5 places to the right.

⇒ 406000 (standard form)

7 × 10³ (scientific notation)

The decimal point moves 3 units to the right.

⇒ 700 (standard form)

5.0 × 10⁻⁴ (scientific notation)

The decimal point moves 4 units to the left.

⇒ 0.0005 (standard form)

8 × 10⁻² (scientific notation)

The decimal point moves 2 units to the left.

0.08 (standard form)

Astatine is predicted to be a solid at 25°C, with the formula of sodium astide being NaAt (solid), and the color of sodium astatide being white. The formula for gaseous astatine is At₂ (gas), and solid astatine is expected to be black in color.

Astatine (At) is located below iodine (I) in Group 17 of the periodic table, also known as the halogens. As we move down the halogen group, the elements become increasingly heavier and more metallic in character. At room temperature, iodine is a solid, and since astatine is located below iodine, it is reasonable to predict that astatine would also be a solid at 25°C.

The formula of sodium astide, which is the compound formed when sodium (Na) reacts with astatine, would be NaAt (solid). Sodium typically forms compounds by losing one electron, and astatine gains an electron to achieve a stable configuration. Thus, sodium astide is formed by the transfer of one electron from sodium to astatine, resulting in the formula NaAt (solid).

Sodium astatide, NaAt (solid), is expected to be white in color. Halides of the alkali metals, such as sodium chloride (NaCl), tend to be white in their solid form, so it can be inferred that sodium astatide would have a similar color.

The formula of gaseous astatine is At₂ (gas). The halogens typically exist as diatomic molecules in their gaseous state, so astatine would be expected to form a diatomic molecule as well.

Solid astatine is predicted to be black in color. As we move down the halogen group, the elements become increasingly darker in color. For example, iodine is a purple-black solid. Since astatine is located below iodine, it is reasonable to predict that solid astatine would be black in color.

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Various gases, including carbon dioxide, methane, and CFCs, are contributing to greenhouse gas emissions, which is the chief factor influencing global climate change.

Greenhouse gases (GHGs) are gases in the Earth's atmosphere that trap heat and contribute to the greenhouse effect. Among the most significant GHGs are carbon dioxide (CO2), methane (CH4), and chlorofluorocarbons (CFCs). These gases have the ability to absorb and re-emit infrared radiation, effectively trapping heat within the Earth's atmosphere. The accumulation of these gases leads to an enhanced greenhouse effect, resulting in global climate change.

Carbon dioxide is primarily generated by the burning of fossil fuels such as coal, oil, and natural gas. Methane is released during the production and transport of coal, oil, and natural gas, as well as from livestock and other agricultural practices. CFCs are synthetic compounds used in various industrial applications, including refrigeration and aerosol propellants. Although their production has been phased out due to their damaging effects on the ozone layer, CFCs have a significant global warming potential.

The increase in greenhouse gas emissions, particularly CO2, CH4, and CFCs, is causing a rise in global temperatures and altering the Earth's climate patterns. This phenomenon, known as global climate change or global warming.

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Answer:

Caesium atoms will form positively charged ions.

Explanation:

Due to them having one electron in their outer orbit, it is very likely that they will give that electron away to form an octet and become stable. Hence, since they lose an electron, they lose a negative charge, and in comparison to their former non-ion self, they have gained a positive charge.

Hence, they will form positively charged ions.

Hope this helped!

Considering the definition of pure substance and homogeneous mixture, the main difference is that a pure substance consists of only one type of particle and it cannot be separated or divided into more substances whereas a homogeneous mixture is made up of two or more different substances and can be separated into various pure substances.

A pure substance is one that is made up of a single type of particle, whether atoms or molecules, and therefore has the same properties in all its parts. The composition and properties of an element or compound are uniform anywhere in a given sample, or in different samples of the same element or compound.

When a substance is made up of two or more simple substances, it is known as a mixture. Homogeneous mixtures are characterized by being formed by two or more components that cannot be distinguished visually. The composition and properties are uniform throughout any given sample, but may vary from sample to sample. In general, the components of a homogeneous mixture can be in any proportion, and can be recovered using physical separation methods.

The main difference between a pure substance and a mixture is that a pure substance consists of only one type of particle and it cannot be separated or divided into more substances whereas a homogeneous mixture is made up of two or more different substances and can be separated into various pure substances.

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a. To find how many moles of OH were added to the buffer solution, we use the following formula: Molarity = (number of moles of solute) / (volume of solution in liters).

Since the molarity of NaOH is 0.100 M, and the volume of NaOH added is 10.0 mL, first convert the volume to liters: 10.0 mL = 0.01 L. Then, use the formula to find the number of moles of NaOH added: 0.100 M = (number of moles of NaOH) / 0.01 L number of moles of NaOH = 0.001 moles. Thus, 0.001 moles of OH were added to the buffer with the addition of the strong base. b. The component of the buffer solution that will react with the added OH is the weak acid (HA). c. The equation for the reaction between the added OH and the weak acid in the buffer is: `OH- + HA → A- + H2O To keep track of how the number of moles changes as a result of the addition of NaOH, we use an ICE table. The ICE table is as follows: OH(aq) → H2O(l) + no. Initially present in buffer: HA = x moles A- = x moles moles of OH added: 0.001 moles change in number of moles during reaction: -0.001 moles moles of each species in the equation that remain AFTER the reaction has occurred: HA = x - 0.001 moles; A- = x + 0.001 moles. d. To determine the new pH of the buffer solution, we use the following formula: `pH = pKa + log([A-] / [HA])`where `pKa` is the dissociation constant of the weak acid, and `[A-] / [HA]` is the ratio of the concentration of the conjugate base to the concentration of the weak acid. The value of `pKa` is given as 4.76, and the concentrations of the conjugate base and weak acid are calculated from the ICE table as follows:`[A-] = (x + 0.001) moles / 0.01 L = (x + 0.001) M` `[HA] = (x - 0.001) moles / 0.01 L = (x - 0.001) M Substituting the values into the formula: pH = 4.76 + log((x + 0.001) / (x - 0.001)) e. If 10.0 mL of 0.100 M NaOH was added to 1000 mL of pure water, then the concentration of OH- would be: Molarity = (number of moles of solute) / (volume of solution in liters)`0.100 M = (number of moles of NaOH) / (0.1 L)number of moles of NaOH = 0.01 moles.

Thus, the number of moles of OH- in the solution is 0.01 moles. The pH of the solution can be found using the formula: pH = 14 - pOH, where `pOH` is the negative logarithm of the concentration of OH-. Thus: pOH = -log(0.01) = 2pH = 14 - 2 = 12Therefore, the pH of the solution would be 12.

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Answer: 10 grams

Explanation: Original sample is 80 gram and every three days half of its composition decays so 80 down to 40 in the first 3 days, 20 in the next three days, and  10 in the last three days

Answer:

When pressure increases, gas volume decreases.

When pressure decreases, gas volume increases.

The ionization constant from the reaction as shown in the calculation is 5.8.

The term ionization constant refers to the extent to which the acid is ionized in solution. It is calculated from;

Ka = [H3O^+] [Cl]/[HCl]

Thus when we substitute the values;

Ka = 13.3 * 7.4/ 16.9

Ka = 5.8

The ionization constant from the reaction as shown in the calculation is 5.8.

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1. The total momentum of the goal keeper and puck after the puck is caught is 6 Kg.m/s

2. The object with the greater momentum is the goal keeper.

1. How do I determine the total momentum of the goal keeper and puck?

We'll begin by obtaining the final velocity of the goal keeper after the puck is caught. This is shown below:

m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂

(0.16 × 40) + (120 × 0) = (0.16 × 0) + (120 × v₂)

6.4 + 0 = 0 + 120v₂

6.4 = 120v₂

Divide both sides by 120

v₂ = 6.4 / 120

v₂ = 0.05 m/s

Finally, we shall determine the total momentum of the goal keeper and puck after the puck is caught. Details below:

Momentum = mass × velocity

Total momentum after collision = m₁v₁ + m₂v₂

Total momentum after collision = (0.16 × 0) + (120 × 0.05)

Total momentum after collision = 6 Kg.m/s

Thus, the total momentum after the puck is caught is 6 Kg.m/s

2. How do I know which object has the greater momentum after the puck is caught?

To know which object has the greater momentum after the puck is caught, we shall determine the momentum of each object after collision. Details below:

Momentum = mass × velocity

Momentum of puck after collision = 0.16 × 0

Momentum of puck after collision = 0 Kg.m/s

Momentum = mass × velocity

Momentum of goal keeper after collision = 120 × 0.05

Momentum of goal keeper after collision = 6 Kg.m/s

From the above calculation, we can conclude that the goal keeper has the greater momentum.

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Worldwide earthquake distribution and geologic forces are closely related. Earthquakes are caused by geologic forces that build up energy within the earth's crust and release it suddenly in the form of seismic waves.

The earth's crust is made up of several plates that are in constant motion. When two plates move towards each other, one plate may be pushed beneath the other in a process known as subduction. This can cause the build-up of pressure and the formation of faults or fractures in the crust, which can lead to earthquakes.

The distribution of earthquakes worldwide is largely determined by the location of these tectonic plate boundaries. For example, most earthquakes occur along the Pacific Ring of Fire, which is an area around the Pacific Ocean where several tectonic plates meet. The Mid-Atlantic Ridge, which is the boundary between the North American and Eurasian plates, is another area where earthquakes are common.

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The major organic product formed in the reaction of 1-methylcyclohexene with diborane in diglyme, followed by basic hydrogen peroxide is 1-methylcyclohexanol.

This reaction is an example of hydroboration-oxidation, which is a common method for the conversion of an alkene into an alcohol. Hydroboration is the addition of borane (BH3) to an alkene to form a trialkylborane.The reaction between 1-methylcyclohexene and diborane (BH3) in diglyme produces trialkylborane as an intermediate product as shown below.

On further reaction with basic hydrogen peroxide (H2O2) as an oxidant, the trialkylborane converts into alcohol as shown below:Thus, the final product obtained after the reaction of 1-methylcyclohexene with diborane in diglyme followed by basic hydrogen peroxide is 1-methylcyclohexanol, which is the major organic product.1-methylcyclohexanol is an organic compound with the molecular formula C7H14O. It is a secondary alcohol with a branched chain. This reaction is widely used in the production of various types of alcohols.

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The balanced chemical equation for the acid-base reaction is:

2HCl + Ca(OH)2 → CaCl2 + 2H2O

A balanced chemical equation is a representation of a chemical reaction that shows the relative number of reactant and product molecules involved. It follows the law of conservation of mass, which states that matter cannot be created or destroyed in a chemical reaction. In a balanced equation, the number of atoms of each element on both sides of the equation is equal.

A balanced chemical equation includes chemical formulas of reactants on the left side of the arrow and the chemical formulas of products on the right side. Coefficients are used to balance the equation by adjusting the number of molecules or moles of each substance involved. These coefficients indicate the relative stoichiometric ratios between reactants and products.

According to the equation, for every 1 molecule of CaCl2 that forms, 2 water molecules are produced. Therefore, the correct answer is:

twice as many, 2x

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The question is mostly solved. The definition of heat is used for this problem which tells us:

Where,

Q is the heat added to the system, 120 J

m is the mass of the metal, 5.0 g

Cp is the specific heat of the metal, 0.385J/g°C

dT is the change of temperature:

T2 is the final temperature, unknown

T1 is the initial temperature, 22°C

We clear the final temperature from the equation:

Now, we replace the known data:

Answer:

The final temperature of the metal will be 84°C

The change in the temperature will be 84°C-22°C=62°C

Answer:

22.4 liters.

Explanation:

The volume occupied by a gas at standard temperature and pressure (STP) can be calculated using the Ideal Gas Law: PV = nRT.

In this equation, P represents the pressure, V represents the volume, n represents the number of moles of gas, R is the universal gas constant (8.31 J/mol*K), and T is the temperature in Kelvin.

At STP, the pressure is 1 atm and the temperature is 0°C (273 K). If we know the number of moles of gas, we can calculate the volume it would occupy at STP.

For 100 grams of oxygen gas, we first need to convert the mass to moles using the molar mass of oxygen (32 g/mol).

So, 100 g / 32 g/mol = 3.125 moles of oxygen.

Then, plugging in the values into the Ideal Gas Law equation:

V = nRT / P

V = (3.125 moles) * (8.31 J/mol*K) * (273 K) / (1 atm)

The volume would be approximately 22 L,


ALLEN

Answer:

When the magma reaches it boiling point and it starts to rise

Explanation: