What is meant by the half-life of a radioactive substance

Answer:

Reaction A:

Reaction B:

Explanation:

Here are some common rules for assigning oxidation states.

For this question, only the rule about neutral compounds, oxygen, and group one metals (K in this case) are needed.

Oxidation states in KNO₃:

Similarly, for KNO₂:

Oxygen is the only element in O₂. As a result,

[tex]\rm\stackrel{+1}{K}\stackrel{\bf +5}{N}\stackrel{\bf -2}{O}_3 \to \stackrel{+1}{K}\stackrel{\bf+3}{N}\stackrel{\bf -2}{O}_2 + \stackrel{\bf 0}{O}_2[/tex].

The oxidation state on two oxygen atoms in KNO₃ increases from -2 to 0. These oxygen atoms are oxidized. KNO₃ is also the reducing agent.

The oxidation state on the nitrogen atom in KNO₃ decreases from +5 to +3. That nitrogen atom is reduced. As a result, KNO₃ is also the oxidizing agent.

Apply these steps to reaction A.

H₂:

O₂:

H₂O:

[tex]\rm \stackrel{}{2}\; \stackrel{\bf 0}{H}_2 + \stackrel{\bf 0}{O}_2\stackrel{}{\to} \stackrel{}{2}\;\stackrel{\bf +1}{H}_2\stackrel{\bf -2}{O}[/tex].

The oxidation state on oxygen atoms decreases from 0 to -2. Those oxygen atoms are reduced. O₂ is thus the oxidizing agent.

The oxidation state on hydrogen atoms increases from 0 to +1. Those hydrogen atoms are oxidized. H₂ is thus the reducing agent.

In the reaction 2H₂(g) + O₂(g) → 2H₂O(l), hydrogen is oxidized and acts as the reducing agent, while oxygen is reduced and acts as the oxidizing agent. Option A is correct.

To identify which species is oxidized and which is reduced in the given reaction 2H₂(g) + O₂(g) → 2H₂O(l), we start by assigning oxidation numbers. Hydrogen is usually +1 (except in metal hydrides, where it is -1), and oxygen is usually -2 (except in peroxides, where it is -1, and in compounds with fluorine, where it is positive). In molecular hydrogen (H₂) and molecular oxygen (O₂), the oxidation numbers are 0 since they are elemental forms.

In water (H₂O), hydrogen has an oxidation number of +1 and oxygen has an oxidation number of -2. Going from 0 in H₂ to +1 in H₂O, hydrogen is oxidized (loses electrons), and going from 0 in O₂ to -2 in H₂O, oxygen is reduced (gains electrons).

Therefore, hydrogen is the reducing agent (it itself gets oxidized), and oxygen is the oxidizing agent (it itself gets reduced).

Hence, A. is the correct option.

Mn’s oxidation number is +4 because the overall compound is neutral/has a 0 charge. So since O always has a -2 oxidation number except in special cases (ex: H2O2) and since oxidation numbers add up to the compound’s charge, x + -2(2) = 0 which means x = 4. thus the oxidation number is 4.

Final answer:

The oxidation number of Mn in MnO2 is +4. This is determined by balancing the total negative charge of -4 from the two oxygen atoms with the positive charge from manganese which must balance to zero in a neutral compound.

Explanation:

The oxidation number of Mn in MnO2 is +4. When determining oxidation numbers, remember that the sum of oxidation numbers in a neutral compound must equal zero. Since each oxygen atom has an oxidation number of -2, and there are two oxygen atoms totaling -4, manganese must have an oxidation number of +4 to balance the charge.

MnO2 is manganese(IV) oxide, indicating that manganese is in the +4 oxidation state. The formula reflects that there are four total electrons that have been transferred to oxygen atoms in this compound, making it less paramagnetic than when manganese is in the +3 state, as seen in manganese(III) oxide, Mn2O3.

The answer is in the photo, but a 0,168 M HCN doesn’t have a pH of 3,15, but 5. HCN real Ka is 6,17*10^(-10).

Answer:

The real answer is 3.00x10^-6

Explanation:

Fill in 3.00 and then -6

Answer:

4.811 atm.

Explanation:

where, P is the pressure of the gas in atm (P = ?? atm).

V is the volume of the gas in L (V = 2.5 L).

n is the no. of moles of the gas in mol (n = 0.5 mol).

R  is the general gas constant (R = 0.0821 L.atm/mol.K),

T is the temperature of the gas in K (T = 20°C + 273 = 293 K).

∴ P = nRT/V = (0.5 mol)(0.0821 L.atm/mol.K)(293 K)/(2.5 L) = 4.811 atm.

Answer:

Neon

Explanation:

1s² 2s² 2p⁶ 3s¹ or [Ne]  3s¹

The outer most shell is the 3s¹.

For this atom to achieve stability, if it loses the electron in the 3s shell, it would resemble an inert element with a complete octet configuration. Therefore, the atom would be like:

                   1s² 2s² 2p⁶ which is the configuration of Ne

Answer:

A chemical reaction is a process that changes one set of chemicals into another set of chemicals. The elements or compounds that enter into the reaction are the ► reactants. The elements or compounds produced by the reaction are the ► products.

The answer is 4), see the picture

The redox equation which is correctly balanced is: 4. [tex]Br_2 + Hg \rightarrow Hg^{2+} + 2Br[/tex]

A redox reaction is also referred to as oxidation-reduction reaction and it can be defined as a type of chemical reaction in which the oxidation number of an atom of participating chemical species are changed.

In this scenario, the oxidation number of an atom of hydrogen is change from one to two. Thus, the redox equation which is correctly balanced is given by [tex]Br_2 + Hg \rightarrow Hg^{2+} + 2Br[/tex]

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Answer : The correct option is, [tex]\frac{10g\text{ of solute}}{100ml\text{ of solution}}\times 100\%[/tex]

Explanation :

The solution concentration expressed in percent by volume means that the amount of solute present in 100 parts volume of solution.

It is represented in formula as :

[tex]\text{Percent solution by volume}=\frac{\text{Amount of solute}}{\text{Amount of solution}}\times 100\%[/tex]

Or,

[tex]\text{Percent solution by volume}=\frac{10g\text{ of solute}}{100ml\text{ of solution}}\times 100\%[/tex]

Hence, the correct option is, [tex]\frac{10g\text{ of solute}}{100ml\text{ of solution}}\times 100\%[/tex]

1 -> theory

2-> law

3->  hypothesis

Answer:

4 mol of KOH would produce 116.6 g of Mg(OH)₂

Explanation:

According to the following balanced equation:

One can note that 2 mol of KOH react with MgCl₂ to produce 1 mol of Mg(OH)₂.

using cross multiplication  

2 mol of KOH → 1 mol of Mg(OH)₂.

4 mol of KOH → ?? mol of Mg(OH)₂.

no of moles of  Mg(OH)₂ = (1 mol* 4 mol) / 2 mol =2 mol

Now we can convert moles of  Mg(OH)₂ to grams using the formula

mass of Mg(OH)₂= (no. of moles * molar mass) = (2 mol * 58.3g/mol) = 116.6 g

Answer:

Energy

Explanation:

A sugar group would be used for carbohydrates or nucleic acids. An adenosine group would be used in ATP formation if I recall correct. And disaccharides are just two monosaccharides linked together, so that would also be for carbohydrates. Therefore, energy is the answer.

Answer:

Explanation:

1) Word equation:

2) Chemical (skeleton) equation:

Include phases but do not balance it (yet). The symbology used is:

3) Balanced chemical equation:

Add the needed coefficients to make the number of atoms of each kind equal on both sides:

The chemical equation that represents hydrogen gas being bubbled through a solution of silver nitrate is: 2AgNO3(aq) + H2(g) -> 2Ag(s) + 2HNO3(aq). This is a redox reaction where silver is reduced and hydrogen is oxidized.

When hydrogen gas is bubbled through a solution of silver nitrate, a chemical reaction occurs. This can be written as a chemical equation:

2AgNO3(aq) + H2(g) -> 2Ag(s) + 2HNO3(aq)

In this equation, hydrogen gas (H2) reacts with silver nitrate (AgNO3) in the solution to form solid silver (Ag) and nitric acid (HNO3). This is a redox reaction, where silver is reduced (gains electrons) and hydrogen is oxidized (loses electrons).

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Answer:

2) at least one multiple carbon-carbon bond.

Explanation:

So, A molecule of an unsaturated hydrocarbon must have 2) at least one multiple carbon-carbon bond.

Answer:

Nitrogen

Explanation:

Answer:

[tex]\boxed{\text{A) Acceleration}}[/tex]

Explanation:

m/s is the unit for speed, so (m/s)/s is the rate of change of speed.  

The rate of change of speed is acceleration.

B), C), and D) are wrong. They all have the units of m/s.

Answer:

12mLd

Explanation:

Given parameters:

Concentration of base, NaOH = 2.0M

Volume of acid, HCl = 24mL = 24 x 10⁻³L = 0.024L

Concentration of HCl = 1.0M

Unknown parameter

Volume of NaOH = ?

The equation of the reaction is NaOH + HCl → NaCl + H₂O

Method

1. Starting the known values, we find the number of moles of acid used. From the reaction equation , we know that:

            1 mole of NaOH reacts with 1 mole of HCl

We use the above to find the number of moles of base used

2. From the number of moles of base, we plug it into the equation below:

              Volume of NaOH = [tex]\frac{number of moles of NaOH}{concentration of NaOH}[/tex]

Solution

Number of moles of acid = concentration of acid x volume of acid

Number of moles = 1M x 0.024L = 0.024mol

              From the balanced equation we know that:

                   1 mole of NaOH reacts with 1 mole of HCl

                   Therefore, the number of moles of NaOH is 0.024mol

Using the equation below, we have:

Volume of NaOH = [tex]\frac{number of moles of NaOH}{concentration of NaOH}[/tex]

Volume of NaoH = [tex]\frac{0.024mol}{2.0M}[/tex]

Volume of NaOH = 0.012L = 12mL

Answer:

2 HCl(aq) + Zn(s) = ZnCl2(s) + H2(g)

Single Replacement Reaction

Answer:

1.332 g.

Explanation:

where, P is the pressure of the gas in atm.

V is the volume of the gas in L.

n is the no. of moles of the gas in mol.

R is the general gas constant,

T is the temperature of the gas in K.

∴ (n) of CO₂ = (n) of C₂H₆

∵ n = mass/molar mass

∴ (mass/molar mass) of CO₂ = (mass/molar mass) of C₂H₆

mass of CO₂ = 1.95 g, molar mass of CO₂ = 44.01 g/mol.

mass of C₂H₆ = ??? g, molar mass of C₂H₆ = 30.07 g/mol.

∴ mass of C₂H₆ = [(mass/molar mass) of CO₂]*(molar mass) of C₂H₆ = [(1.95 g / 44.01 g/mol)] * (30.07 g/mol) = 1.332 g.

The mass of 1 liter of C2H6 gas at the same temperature and pressure as the CO2 can be calculated using Avogadro's principle and the proportionality of molar masses. You set up a proportion using the molar masses of CO2 and C2H6 and the given weight of CO2 to solve for the weight of C2H6 gas.

First, you need to understand the concept of molar mass and Avogadro's principle. Avogadro's principle states that equal volumes of all gases, at the same temperature and pressure, have the same number of molecules.

The molar mass of CO2 is approximately 44.01 g/mol. Given that one liter of CO2 gas weighs 1.95g, we can calculate the molar volume of a gas at the given temperature and pressure. Because the weights will be proportional, we can use the molar mass of C2H6 to find the weight of 1 liter of C2H6 gas.

Since the molar mass of C2H6 (ethane) is approximately 30.07 g/mol, you can set up the proportion as follows: 44.01 / 1.95 = 30.07 / X. Solving this equation gives you the weight of C2H6.

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Answer:

Explanation:

Endothermic means that the process makes that the system (substance) absorbs heat energy from the surroundings. In this case the heat is supplied to the ice (from a flame for example). So, the ice is absorbing this heat.

In general, the phase change from solid (ice) to liquid is endothermic because the solid substance has a lower kinetic energy than the liquid particles. So, the solid must gain energy (which is supplied in the form of heat) to become liquid.

The reason why the solid particles have lower kinetic energy than liquid ones is that the particles vibrate and translates quicker in the liquid state than in the solid state.

1) B) continuous direct.

2) B) oscillator.

3) C) Bismuth.

6) I dont know this one sorry :/

8) B) The electric potential (volts) divided by the current (amperes) equals the resistance (ohms).

11) D) 30 V

13) A) Each of the two segments of the original bar magnet will have a north and south pole.

16) C) Shortening the conductor.

Because of its high solubility, water is considered to be a universal solvent.

A substance that displaces most compounds is known as a universal solvent. Because it dissolves more chemicals than any other solvent, water is known as the universal solvent. But no solvent, not even water, can dissolve all chemicals. According to the principle of "like dissolves like," polar solvents typically dissolve polar compounds, such as salts.

Nonpolar solvents may dissolve organic molecules like lipids and other nonpolar substances. Because of its polar nature, which gives each molecule a hydrophobic (water-fearing) and hydrophilic (water-loving) side, water dissolves more compounds than any other solvent.

The oxygen atom has a tiny negative electrical charge, whereas the side of the molecules with two hydrogen atoms carries a slight positive electrical charge. Water's polarisation makes it possible for it to draw in a wide variety of molecules. Water is able to split the substance into its ions due to the strong attraction to ionic molecules like sodium chloride or salt.

Therefore, water is considered a universal solvent.

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Answer:

4

Explanation:

Protein synthesis involves two major steps:

Transcription involves the formation of a nucleotide sequence complementary to the DNA molecule, with the pairing of a different base, Uracil, with Guanine instead of the usual Thymine base. This occurs in the nucleus of the cell, and the resulting molecule is known as the mRNA.

This mRNA is transported into the cytoplasm through the nuclear pore for the next step, translation. This is primarily accomplished by ribosomes and tRNA molecules which are present in the cytoplasm of the cell. The result of this step is the generation of a protein molecule.

Answer:

its A, C and E (1, 3, 5)

i did this on edgenuiti and it was correct =)

mark as brainliest i really need it bc if not i'll never level up i have 797/500 points

Answer:

Explanation:

Assume 100% ionization:

1) 0.100 M solution K₂SO₄

This means, that you have to find which of the choices is a solution that contains the same 0.300 M ion concentration.

2) 0.0800 M Na₂CO₃

This is not equal to 0.300 M, so this solution would not contain the same total concentration as a 0.100 M solution of K₂SO₄, and is not the right answer.

3)  0.100 M NaCl

This is not equal to 0.300 M ion, so not a correct option.

4) 0.0750 M Na₃PO₄

Hence, this ion concentration is equal to the ion concentration of a 0.100 M solution of K₂SO₄, and is the correct choice.

5)  0.0500 M NaOH

Not equal to 0.300 M, so wrong choice.

A 0.100 M solution of K₂SO₄ has the same total ion concentration as a 0.0750 M solution of Na₃PO₄, both resulting in 0.300 M of ions.

K₂SO₄ dissociates into 2K⁺ and (SO₄)²⁻. Thus, a 0.100 M solution of K₂SO₄ produces 0.200 M K⁺ (2 x 0.100 M) and 0.100 M (SO₄)₂⁻, resulting in a total ion concentration of 0.300 M.

Let’s analyze the other solutions:

The correct answer is 0.0750 M Na₃PO₄, as it also produces a total ion concentration of 0.300 M.

Answer:

Explanation:

The changing of substances to other substances by the breaking of bonds in reactants and the formation of bonds in products is the definition of chemical change or reaction.

Chemical reactions or cahnges are the transformation of pure substances, compounds or elements, into other substances by the breaking of some bonds adn the formation of other bonds.

The chemical reactions are represented by chemical equations with the reactants in the left side and the products in the right side, connected by  the use of arrows.

For example, the chemical equation CH₄ (g) + O₂(g) → CO₂(g) + H₂O(g) represents the combustion reaction (chemical change) of methane (CH₄) with oxygen (O₂).

The products of the reaction are carbon dioxide (CO₂) and water (H₂O) which are the new substances formed by breaking the chemical bonds in CH₄ and O₂ and the formation of the bonds in the new molecules (CO₂ and H₂O).

Chemical equation: CH₄ (g) + O₂(g)  →  CO₂(g) + H₂O(g)

                                    ↑           ↑               ↑             ↑

                                 -- reactants --         --- products --

The reactants have been transformed into different chemical compounds, so  this is a chemical changle.

Chemical reactions involve the changing of substances through the breaking and formation of bonds. Reactants are the starting substances, while products are the resulting substances. The direction of the reaction is indicated by an arrow.

Chemical reactions occur when two or more atoms bond together to form molecules or when bonded atoms are broken apart. The substances used in a chemical reaction are called the reactants (usually found on the left side of a chemical equation), and the substances produced by the reaction are known as the products (usually found on the right side of a chemical equation). An arrow is typically drawn between the reactants and products to indicate the direction of the chemical reaction; this direction is not always a 'one-way street.'

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Answer:

[tex]\boxed{\text{30 mL}}[/tex]

Explanation:

Step 1. Calculate the moles of NaOH

[tex]n = \text{60.0 kg} \times \dfrac{\text{0.0010 mol}}{\text{1 kg}} = \text{0.0600 mol}[/tex]

Step 2. Calculate the volume of NaOH

[tex]V = \text{0.0600 mol} \times \dfrac{\text{1 L}}{\text{2.0 mol}} = \text{0.030 L} = \text{30 mL}\\\\\text{The lethal volume of NaOH is } \boxed{\textbf{30 mL}}[/tex]

Final answer:

To find the lethal volume of a 2.0M NaOH solution for a 60kg person, calculate the total lethal dose (0.060 mol) and then divide by the concentration (2.0M), resulting in 30 mL.

Explanation:

The question involves calculating the lethal volume of a 2.0M NaOH solution for a 60kg person based on the lethal dose (LD50) of NaOH, which is 0.0010 mol/kg. First, we need to determine the total lethal dose of NaOH for the person:

Therefore, the lethal volume of a 2.0M NaOH solution for a 60kg person is 30 mL.

Answer:

5 moles

Explanation:

This reaction (in the question) is a combustion reaction.

A combustion reaction is a reaction in which a substance (in this case an organic compound) is burnt in excess oxygen to produce carbon dioxide and water.

From the equation in the question, it can be deduced that the moles of the products are in the ratio 1:2 for CO₂ and H₂O respectively. Hence, when 10 moles of H₂O is produced, 5 moles of CO₂ will be produced.

1:2      (from the equation)

5:10   (for the answer)  ⇔ which is still the same as 1:2

Answer:

H₂0[tex]_{(s)}[/tex]  +  heat  →  H₂O[tex]_{(l)}[/tex]  

Explanation:

An ENDOTHERMIC reaction is a chemical reaction in which heat is absorbed by the reactants. As such the product is usually cooler than the products. In the equation above (the answer), heat is on the reactant side of the equation thus indicating that heat is absorbed by the reactants.

On the other hand, in the first equation heat is on the product side of the equation which is consistent with an Exothermic reaction.

Explanation :

In thermodynamics, a system is region or part of space which is being studied and observed while the surrounding is the region or space around the system which interacts with the system.

Here in the experiment ,system which is observed is reaction or changes when citric acid and sodium bicarbonate are mixed together. And the mixing is carried out in the calorimeter which serves as a surrounding around the system.

The reason behind the using the calorimeter is measure the energy change occurring during the reaction.

Answer:

0.139

Explanation:

First find how many moles of h2o give you 10g then use the mole ratio to find what mole of c3h8 is required to get you that number of moles

Answer:

0.139 moles of C3H8 must be reacted to form exactly 10.0 g of H2O

Explanation:

The rule of three or is a way of solving problems of proportionality between three known values and an unknown value, establishing a relationship of proportionality between all of them. That is, what is intended with it is to find the fourth term of a proportion knowing the other three. Remember that proportionality is a constant relationship or ratio between different magnitudes.

If the relationship between the magnitudes is direct, that is, when one magnitude increases, so does the other (or when one magnitude decreases, so does the other) , the direct rule of three must be applied. To solve a direct rule of three, the following formula must be followed:

a ⇒ b

c ⇒ x

[tex]x=\frac{c*b}{a}[/tex]

It is possible to use the reaction stoichiometry of the reaction (that is, the relationship between the amount of reagents and products in a chemical reaction) and the rule of three to determinate the moles of C₃H₈ that must be reacted to form exactly 10.0 g of H₂O.  But first you must know the amount of moles that represent the 10 g of H₂O.

You know that:

Then,  the mass of H₂O is 2*1 g/mol + 16 g/mol= 18 g/mol

Then it is possible to apply a rule of three: if 1 mole of H₂O contains 18 grams, how many moles will contain 10 grams?

[tex]moles of H2O=\frac{10 grams*1 mole}{18 grams}[/tex]

moles of H₂O=0.556

Then, to determine the moles of C₃H₈ that must react to form exactly 10.0 g of H₂O it is possible to use a rule of three, as previously mentioned: if by stoichiometry 4 moles of H₂O are formed from 1 moles of C₃H₈, when are formed 0.55 moles of H₂O How many moles of C₃H₈ will be needed?

[tex]moles of C3H8=\frac{0.556molesofH2O*1molesofC3H8}{4molesofH2O}[/tex]

moles of C₃H₈= 0.139

Finally, 0.139 moles of C3H8 must be reacted to form exactly 10.0 g of H2O

Answer:

Explanation:

You can calculate the oxidation number of most elements following some simple rules.

This is how you do it for chromium in K₂Cr₂O₇.

1) Rule: in a neutral compound the net oxidation number is zero (0).

Hence, sum of the oxidation numbers of K, Cr and O in K₂Cr₂O₇ is 0.

2) Rule: The most common oxidation number of oxygen in compounds, except in peroxides, is  2 ⁻ (negative 2).

3) Rule: the most common oxidation state of alkali metals is 1⁺ (positive 1)

4) Rule: multiply each oxidation state by the corresponding number of atoms in the compound (the subscripts)

          ↑         ↑       ↑

          K        Cr      O

Hence, the oxidation number of chromium in this compound is 6⁺.

The oxidation number of chromium in K2Cr2O7 (potassium dichromate) is +6. This is determined by knowing that potassium has an oxidation number of +1, oxygen has an oxidation number of -2, and the sum of the oxidation numbers of the chromium atoms must balance the charge contributed by potassium and oxygen to make the compound neutral.

The oxidation number of chromium in K2Cr2O7 requires some calculation using the rules of oxidation states. Firstly, potassium (K) has an oxidation number of +1, and each oxygen (O) has an oxidation number of -2. In the compound K2Cr2O7, there are two potassium atoms contributing a total of +2 to the charge of the compound. There are seven oxygen atoms each contributing -2, for a total of -14. Since the compound is neutral overall, the sum of the oxidation numbers of the chromium atoms must balance the negative charge contributed by the oxygen. Therefore, the total oxidation state for the two Cr atoms must be +12 in order to have a net charge of zero when added to the oxidation states of potassium and oxygen. Dividing this by two, since there are two chromium atoms, gives an oxidation number of +6 for each chromium atom.

Additionally, in the reduction half-reaction, Cr2O72- is reduced to Cr3+ with each chromium atom being in the +6 oxidation state initially. The chemical reaction involving the conversion of Fe2+ to Fe3+ supported by potassium dichromate provides further evidence that each chromium atom has an initial oxidation state of +6.