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The mass number of an atom of potassium that has 20 neutrons is option C. 39

Mass number-

Mass number is the total number of protons and neutrons in the nucleus of an atom is called the mass number. It is represented by the symbol A. In other words, mass number refers to the sum of the number of protons and neutrons in the nucleus of an atom.

Atom-

Atoms are tiny particles that make up everything in the world. Everything in the world is made up of tiny particles known as atoms. An atom is the basic unit of matter. The term "atom" comes from the Greek word atomos, which means indivisible.

The basic building blocks of all matter are atoms, which are made up of three types of particles: protons, neutrons, and electrons.

In a neutral atom, the number of electrons is equal to the number of protons, thus the overall charge on the atom is zero. However, the mass number of the atom is equal to the sum of the number of protons and neutrons.

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pH is the measurement of the intensity of a solution of how much it is acid or base. Acid has a pH of less than 7 and the base has a pH of more than 7. The solution is neutral at pH 7.

1. Given information,

The hydrogen ion concentration ([H⁺]) of a solution = 8.9 × 10⁻⁷ mol/L.

pH = -log[H⁺]

pH = -log(8.9 × 10⁻⁷) = -(-6.05) = 6.05

2. Given information,

The pH of a solution = 12.35

[H⁺] = 10^(-pH)

[H⁺] = 10^(-12.35) ≈ 4.21 × 10⁻¹³ mol/L

Therefore, the pH of the solution is 6.05 and the hydrogen ion concentration of the solution is approximately 4.21 × 10⁻¹³ M.

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The given statement " the floor value of a convertible bond is its conversion value " is False.

The floor value of a convertible bond is not necessarily its conversion value. The floor value refers to the minimum value that a convertible bond should have, regardless of the underlying stock's performance. It is typically determined by factors such as the bond's coupon rate, time to maturity, and prevailing interest rates.

The conversion value, on the other hand, is the value that a convertible bond would have if it were immediately converted into shares of the underlying stock. It is calculated by multiplying the conversion ratio (the number of shares received upon conversion) by the market price of the underlying stock.

While the conversion value can serve as a lower bound for the value of a convertible bond, the floor value takes into account additional factors and is not solely based on the conversion value.

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A balanced equation obey the law of conservation of mass, the mass can neither be converted nor  be destroyed but can converted from one form to another. Here the given reaction indicates Haber process.

The ratio of the product of concentrations of the products to that of the reactants is also known as the concentration quotient and it is denoted as Q. At equilibrium Q becomes equal to the equilibrium constant.

The Haber process is:

N₂ + 3H₂ → 2NH₃

Q = [NH₃]² / [N₂] [H₂]³

Q = [0.0596]² / [0.600] [0.420]

Q = 0.014

Here Q is less than K, so the reaction proceeds in the forward direction.

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To keep burning, fires require oxygen. Carbon dioxide is used in certain fire extinguishers to put out flames. Explanation: Because magnesium is higher on the reactivity scale than carbon, it is more reactive and eliminates oxygen from carbon dioxide (to give carbon and magnesium oxide).

There are 4 outcomes of rolling two numbers with a sum of less than 6.To find the number of outcomes of rolling two numbers with a sum less than 6, we need to consider the possible combinations of dice rolls that would result in a sum less than 6.

To determine the outcomes that have a sum less than 6, we can list out all the possible combinations of dice rolls that would result in a sum less than 6: There are a total of 6 combinations that would result in a sum less than 6.
However, since we are rolling two dice simultaneously, we need to take into account the fact that each of these combinations can occur in two different orders (i.e. rolling a 1 and a 2 is the same as rolling a 2 and a 1).

Therefore, we need to multiply the number of combinations by 2 to get the total number of outcomes: 6 x 2 = 12 However, we must also keep in mind that the question is asking for the number of outcomes, not the number of combinations. This means that we need to divide the total number of outcomes by 2 to account for the duplicate combinations: 12 / 2 = 6 So the final answer is that there are 4 outcomes of rolling two numbers with a sum less than 6.

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Answer:

2 sublevels

Explanation:

n=2 is the principal energy level witch contain sublevel 2s and 2p

Answer:

Thus, the joules of heat absorbed when 70.0 grams of water is completely vaporised at its boiling point are 158,200.

decay rate of approximately 1.69x10^17 Bq (becquerels),

The decay rate of a radioactive sample is determined by the number  of radioactive atoms present and the decay constant, which represents the probability of decay per unit of time.

To calculate the decay rate, we multiply the number of atoms in the sample by the decay constant. In this case, the sample has 8.31x10^17 atoms and a decay constant of 0.203/s. Multiplying these values gives a decay rate of approximately 1.69x10^17 Bq (becquerels), which represents the number of decays per second in the sample.

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Each cell has 23 pairs of chromosomes.

The nucleus of each cell contains the chromosome, and it can be defined as packaged into thread-like structures. Each chromosome is structurally composed of DNA that is tightly coiled around special proteins. The chromosomes are typically not visible under the microscope.

All living organisms possess chromosomes. The human body has 23 pairs of chromosomes. Out of the 23 pairs of chromosomes, 22 pairs of these chromosomes are known as autosomes.

These are identical in both males and females while the 23rd pair of chromosomes are known as allosomes. This pair differs between the sexes. Females have two copies of the “X” chromosome while males have one “X” and “Y” chromosome.

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The largest buffering capabilities of monoamino monocarboxylic acids are found in the two pH ranges closest to their two pK′ values, namely pH 2.3 and pH 9.7.

Buffer capacity measures a solution's ability to tolerate pH fluctuations by either absorbing or desorbing H+ and OH- ions. The effect of adding an acid or base to a buffer system on pH change can be considerable or modest, depending on both the starting pH and the buffer's ability to resist pH change.

A good buffer combination should include roughly equal amounts of both components. As a general rule, a buffer solution is no longer helpful when one component of the buffer pair is less than around 10% of the other.

If the buffer capacity is increased by tenfold, the buffer solution may absorb ten times more strong acid or base before experiencing a noticeable pH shift. When an acid or basic is introduced to a solution, a buffer maintains a reasonably constant pH.

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A battery is a device that converts chemical energy into electrical energy through a process known as an electrochemical reaction.

When a battery is connected to a circuit, the electrochemical reaction causes a flow of electrons from the anode to the cathode, generating an electric current that can power a device.

The metal chosen for the anode must be capable of losing electrons easily, while the metal chosen for the cathode must be capable of accepting electrons. The choice of metals can also affect the voltage and capacity of the battery, as well as its overall efficiency.

In general, the metals used in a battery should have a large difference in their electronegativity values, which determines how easily an atom can attract electrons. Common metals used in batteries include zinc, lithium, nickel, and cadmium.

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Answer:

Index fossil, any animal or plant preserved in the rock record of the Earth that is characteristic of a particular span of geologic time or environment.

Explanation:

True

Answer:  

Explanation:

If you use Copper (Cu) as the metal , Oxygen (O) and Carbon (C) as the c, then you can make 2 new compounds in five minutes.

The two possible compounds are:

Copper oxide (CuO) is a chemical compound composed of copper and oxygen. It is a black, solid material with a high melting point and is commonly referred to as cupric oxide or black oxide of copper.

CuO can be produced by heating copper in the presence of oxygen, or by reacting copper sulfate with sodium hydroxide. It is commonly used as a raw material in the production of copper salts, in the manufacturing of ceramics, as a pigment, and as a catalyst in various chemical reactions.

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Answer: they don't have values there because they aren't on the pauling scale of electronegativity, as they don't form any compounds with other elements. However, argon and neon can technically form compounds with other elements; it is just extremely unlikely.

Explanation:

Water is an example of a balanced synthesis equation: 2 H2(g) + O2(g) → 2 H2O(g). The number of atoms in the reactants and the number of atoms in the products must balance in a chemical equation.

A chemical reaction equation is said to be balanced if both the reactants and the products have the same total charge and the same number of atoms in the reaction. In other words, both sides of the reaction have an equal mass and charge balance.

The Law of Conservation of Mass states that mass cannot be created or destroyed in a chemical reaction. On the left and right sides of a balanced chemical equation, there are an equal number of atoms of each element.

Therefore,

Water: 2 H2(g) + O2(g) → 2 H2O(g)

2K + 2H2O → 2KOH + H.

NaCN ( a q ) + HBr ( a q ) → NaBr ( a q ) + HCN ( g )

2HgO(s)→2Hg(l)+O2(g)

2CH3OH + 3O2 → 4H2O + 2CO2

HCl(aq)+NaOH(aq)⇌NaCl(aq)+H2O

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Answer:

After three hours, concentration of C₂F₄ is 0.00208M

Explanation:

The rate constant of the reaction:

2 C2F4 → C4F8 is 0.0410M⁻¹s⁻¹

As the units are M⁻¹s⁻¹, this reaction is of second order. The integrated law of a second-order reaction is:

\(\frac{1}{[A]} =\frac{1}{[A]_0} +Kt\)

Where [A] and [A]₀ represents initial and final concentrations of the reactant (C₂F₄), K is rate constant (0.0410M⁻¹s⁻¹) and t is time of the reaction (In seconds).

3.00 hours are in seconds:

3 hours ₓ (3600 seconds / 1 hour) = 10800 seconds

Initial concentration of C2F4 is:

0.105mol / 4.00L = 0.02625M

Replacing in the integrated law:

\(\frac{1}{[A]_0}= \frac{1}{0.02625} +0.0410M^{-1}s^{-1}*10800s\\\frac{1}{[A]_0}=480.9M^{-1}\)

[A] = 0.00208M

Answer:

For scientists working in classified areas, collaboration with university programs and researchers provides opportunities to expand their career opportunities and strengthen their science through the conduct of peer-reviewed, open literature research.

Explanation:

that's just how it works!

Answer:

Adding on to the previous answer, having collaboration allows you to broaden your scopes, and science is all about just collaborating and communicating with each other. We discuss with other fellow scientists about research to get different perspectives or to get advice. It's practically useful since you are all interdependently relying on each other while sharing what you know.

Answer:

Earth’s tectonic plates fit together in a jigsaw puzzle of plate boundaries.

The Earth’s outer shell, the lithosphere, consisting of the crust and uppermost mantle, is divided into a patchwork of large tectonic plates that move slowly relatively to each other. There are 7-8 major plates and many minor plates. Varying between 0 to 100mm per year, the movement of a plate is driven by convection in the underlying hot and viscous mantle.

Explanation:

Answer:

B. Moderately active metal

Explanation:

Direct expansion systems require the vapour exiting the evaporator to be superheated to avoid liquid slugging, to improve the effectiveness of the evaporator and to maintain the stability of the compressor. (B) Forced draft and induced draft evaporators differ in the way air is introduced into them. (C) CClF2CF3 (also known as R12) is a chlorofluorocarbon refrigerant. (ii) Tetrafluoroethane (also known as R134a) is a hydrofluorocarbon refrigerant and H2O is not classified as a refrigerant. (D) The partial pressure of hydrogen in the evaporator is 1.6 mmHg.

(a) Direct expansion systems are those in which the refrigerant in the evaporator evaporates directly into the space to be cooled or frozen. The evaporator superheat is used to make sure that only vapor and no liquid is carried over into the suction line and compressor. Superheating is required for the following reasons :

(b) Forced draft and induced draft evaporators differ in the way air is introduced into them. In an induced draft evaporator, a fan or blower is positioned at the top of the evaporator, and air is drawn through the evaporator from the top. In a forced draft evaporator, air is propelled through the evaporator by a fan or blower that is located at the bottom of the evaporator. Forced draft evaporators are frequently used in direct expansion systems because they allow for better control of the air temperature. Because the air is directed upward through the evaporator and out of the top, an induced draft evaporator is less effective at keeping the air at a uniform temperature throughout the evaporator.

(c) (i) CClF2CF3 (also known as R12) is a chlorofluorocarbon refrigerant.

(ii) Tetrafluoroethane (also known as R134a) is a hydrofluorocarbon refrigerant.

(iii) H2O is not classified as a refrigerant.

(d) The function of hydrogen gas in an absorption refrigeration system (NH3/H2O/H2) is to increase the heat of reaction between ammonia and water.

The pressure of hydrogen gas in the evaporator of an absorption refrigeration system can be determined using the formula, Pa/Pb = (Ta/Tb)^(deltaS/R),

where Pa = partial pressure of hydrogen in the evaporator, Ta = evaporating temperature, Tb = condensing temperature, Pb = partial pressure of hydrogen in the absorber, deltaS = entropy change between the absorber and evaporator, R = gas constant.

Substituting the given values, Ta = −2.0 ∘C = 271 K ; Tb = 38.0 ∘C = 311 K ; Pb = atmospheric pressure = 1 atm ;

deltaS = 4.7 kJ/kg K ; R = 8.314 kJ/mol K

we get, Pa/1 atm = (271/311)^(4.7/8.314)

Pa = 0.021 atm or 1.6 mmHg

Therefore, the partial pressure of hydrogen in the evaporator is 1.6 mmHg.

Thus, Direct expansion systems require the vapour exiting the evaporator to be superheated to avoid liquid slugging, o improve the effectiveness of the evaporator and to maintain the stability of the compressor. (B) Forced draft and induced draft evaporators differ in the way air is introduced into them. (C) CClF2CF3 (also known as R12) is a chlorofluorocarbon refrigerant. (ii) Tetrafluoroethane (also known as R134a) is a hydrofluorocarbon refrigerant and H2O is not classified as a refrigerant. (D) The partial pressure of hydrogen in the evaporator is 1.6 mmHg.

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Answer: todos terminan en tu boca

Explanation:

Hahaha

Answer:

1. 2Mg + O2 —> 2MgO

2. 2H2 + O2 —> 2H2O

3. CH4 + 2O2 —> CO2 + 2H2O

Explanation:

1. Magnesium + Oxygen —> Magnesium Oxide

Mg + O2 —> MgO

There are 2 atoms of O on the left side and 1 atom on the right side. It can be balance by putting 2 in front of MgO as shown below:

Mg + O2 —> 2MgO

There are 2 atoms of Mg on the right side and 1 atom on the left side. It can be balance by putting 2 in front of Mg as shown below:

2Mg + O2 —> 2MgO

Now the equation is balanced.

2. Hydrogen + Oxygen —> Water

H2 + O2 —> H2O

There are 2 atoms of O on the left side and 1 atom on the right side. It can be balance by putting 2 in front of H2O as shown below:

H2 + O2 —> 2H2O

There are 2 atoms of H on the left side and a total of 4 atoms on the right side. It can be balance by putting 2 in front of H2 as shown below:

2H2 + O2 —> 2H2O

Now, the equation is balanced.

3. Methane + oxygen à Carbon dioxide + Water

CH4 + O2 —> CO2 + H2O

There are 4 atoms of H on the left side and 2 atoms on the right side. It can be balance by putting 2 in front of H2O as shown below:

CH4 + O2 —> CO2 + 2H2O

There are 2 atoms of O on the left side and a total of 4 atoms on the right side. It can be balance by putting 2 in front of O2 as shown below:

CH4 + 2O2 —> CO2 + 2H2O

Now, the equation is balanced.

Answer:

8.14 mols al

Explanation:

The Sun's chemical composition 3 billion years ago. To explain the difference,  focus on three aspects: the amount of hydrogen, the presence of water, and the star's apparent brightness and spectral type.

1. More hydrogen: 3 billion years ago, the Sun had a higher concentration of hydrogen compared to now. Hydrogen is the primary fuel for nuclear fusion in the Sun's core, where it converts into helium. Over time, as hydrogen is used up in this process, its overall percentage in the Sun's composition decreases.

2. Presence of water: Although it's unlikely that the Sun had significant amounts of water 3 billion years ago, it might have had trace amounts of water vapor. However, due to the Sun's high temperature, water molecules would have quickly dissociated into hydrogen and oxygen atoms.

3. Apparent brightness and spectral type: The Sun's brightness and spectral type have evolved over time. 3 billion years ago, the Sun was a bit cooler and less luminous, classified as a G-type main sequence star. As it consumed hydrogen and underwent nuclear fusion, its core contracted and its outer layers expanded, causing the Sun to heat up and become brighter over time. This has led to the Sun's current classification as a G2V type star.

The chemical composition of the Sun 3 billion years ago was different from today, with more hydrogen, possibly trace amounts of water, and a different apparent brightness and spectral type due to its stage in the stellar evolution process.

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Answer:

113 because there are 113 elements

Explanation:

The balanced chemical equation for this titration is:

AgNO3 + Cl- → AgCl + NO3-

From the equation, we can see that 1 mole of AgNO3 reacts with 1 mole of Cl-. Therefore, the number of moles of Cl- in the water sample is equal to the number of moles of AgNO3 used in the titration.

Number of moles of AgNO3 = concentration × volume = 0.104 M × 27.2 mL = 2.8448 × 10^-3 moles

Since the volume of the water sample is 25.0 mL or 0.0250 L, the concentration of Cl- in the sample is:

Concentration of Cl- = number of moles / volume = 2.8448 × 10^-3 moles / 0.0250 L = 0.1138 M

Therefore, the concentration of Cl- in the water sample is 0.1138 M.

The three industries commonly associated with battery technology are the automotive, electronics, and renewable energy sectors. Each of these industries faces specific challenges when it comes to developing better batteries.

Automotive Industry:

Electronics Industry:

Renewable Energy Industry:

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