Which of the following is an exothermic reaction?

A) melting ice

B) iron rusting

C) dissolving sugar in water

D) dissolving ammonium nitrate in water

Answer: Option (C) is the correct answer.

Explanation:

As nitrogen is a group 15 element so, it means that common electronic distribution of elements of group 15 will be 2, 8, 5.

Hence, it means that all the elements of group 15 have 5 valence electrons.

Valence electrons are the electrons that are present in the outermost orbital shell.

Whereas atomic number of nitrogen atom is 7 and its atomic mass is 14. Therefore, it contains 7 protons and 7 neutrons in its nucleus.

Thus, we can conclude that nitrogen is a group 15 element it implies that nitrogen has 5 valence electrons.

Answer:

Explanation:

The equation of this equilibrium reaction is shown below:

     CH₄ + 2H₂S ⇄ CS₂ + 4H₂

All the gases in this reaction are in a gaseous phase.

When gases are in equilibrium with one another, we can make some comments about their particles, concentration and reaction rate.

For the particles:

The magnitude of the kinetic energy here is very great according to the kinetic theory of matter. This is because the particles are in a uniform gaseous phase.

In terms of concentration

When dealing with gases in equilibrium, we talk more of the concentration with regards to pressure. Pressure is equivalent to concentration when we consider gaseous reactions. An increase in pressrue is like applying a stress to the system. Based on Le Chatelier's principle, increase in pressure favors the side with smaller volume:

                       CH₄             +         2H₂S           ⇄ CS₂        + 4H₂

                        3 moles of gases                          5 moles of gases

Increase in pressure will favor the reactant side.

Reaction rate

The rate at which this reaction will proceed would be very fast. This is because gases have the fastest rate of reaction. The equilibrium will quickly be reached.

Weight training has the biggest effect on skeletal muscles.

A muscle fibre is another term for a single skeletal muscle cell, which is not the same as skeletal muscle. The many muscle fibres that make up skeletal muscles are bound together by connective tissue. The contraction of each muscle fibre, which is made up of a single multinucleated cell, results in force and movement.

A specific form of cell called a muscle fibre sometimes referred to as a myofiber or muscle cell, is what gives skeletal muscles their shape. Long, cylindrical cells called muscle fibres make up a muscle's length and are bound together by connective tissue. Since they have several nuclei, they are multinucleated cells, which may contract to provide force and movement.

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Answer:

B. Opening a door for someone who is carrying things

Answer: there must be 64 g + 24 g = 88 g of carbon dioxide present after the reaction.

Explanation: Since the total mass of substances used up in the reaction must be equal to the amount of product formed, according to the conservation of mass law,

Answer:

chloroplast

Explanation:

chloroplasts

In plants, photosynthesis takes place in chloroplasts, which contain the chlorophyll. Chloroplasts are surrounded by a double membrane and contain a third inner membrane, called the thylakoid membrane, that forms long folds within the organelle.

Answer:

[tex]\boxed{\text{3.6 atm}}[/tex]

Explanation:

For this question, we must use Dalton's Law of Partial Pressures:

The partial pressure of a gas in a mixture of gases equals its mole fraction times the total pressure:

[tex]p = \chi p_{\text{tot}}[/tex]

1. Calculate the number of moles of each gas.

[tex]n_{\text{CO}_{2}} = \text{35.07 g} \times \dfrac{\text{1 mol}}{\text{44.01 g}} = \text{0.7969 mol}\\\\n_{\text{H}_{2}\text{O}} = \text{27.93 g} \times \dfrac{\text{1 mol}}{\text{18.02 g}} = \text{1.550 mol}\\\\n_{\text{N}_{2}} = \text{12.64 g} \times \dfrac{\text{1 mol}}{\text{14.01 g}} = \text{0.9022 mol}\\\\n_{\text{He}} = \text{5.54 g} \times \dfrac{\text{1 mol}}{\text{4.003 g}} = \text{1.384 mol}[/tex]

2. Calculate the total moles

[tex]n_{\text{tot}} = \text{(0.7969 + 1.550 + 0.9022 + 1.384) mol = 4.633 mol}[/tex]

3. Calculate the mole fraction of helium

[tex]\chi = \dfrac{n_\text{He}}{n_{\text{tot}}} = \dfrac{\text{1.384 mol}}{\text{4.633 mol}}= 0.2987[/tex]

4. Calculate the partial pressure of helium:

[tex]p_{\text{He}} = \chi_{\text{He}} p_{\text{tot}}= 0.2987 \times \text{12 atm} = \textbf{3.6 atm}\\\\p_{\text{He}} = \boxed{\textbf{3.6 atm}}[/tex]

Answer:

The partial pressure of He = 3.97 atm

Explanation:

Given:

Mass of CO2 = 35.07 g

Mass of H2O = 27.93 g

Mass of N2 = 12.64 g

Mass of He = 5.54 g

Total pressure P = 12 atm

To determine:

The partial pressure of He

Calculation:

Based on Dalton's law, the partial pressure of a gas can be expressed as a product of its mole fraction and the total pressure

[tex]P(gas)=X(gas)*P(total)-----(1)[/tex]

where X(gas) = mole fraction

[tex]X(gas)=\frac{moles(gas)}{moles(total)}----(2)[/tex]

[tex]Moles(CO2)=\frac{mass(CO2)}{mol.wt.(CO2)}=\frac{35.07g}{44g/mol}=0.7970[/tex]

[tex]Moles(H2O)=\frac{mass(H2O)}{mol.wt.(H2O)}=\frac{27.93g}{18g/mol}=1.552[/tex]

[tex]Moles(N2)=\frac{mass(N2)}{mol.wt.(N2)}=\frac{12.64g}{28g/mol}=0.4514[/tex]

[tex]Moles(He)=\frac{mass(He)}{at.wt.(He)}=\frac{5.54g}{4g/mol}=1.385[/tex]

Therefore:

Moles of He = 1.385

Total moles = 0.7970+1.552+0.4514+1.385 =4.188

Substituting the appropriate values in equation (1) gives:

[tex]P(He)=X(He)*P(total)[/tex]

[tex]P(He)=\frac{1.385}{4.188}*12 atm = 3.97 atm[/tex]

Answer:

Mutual coagulation takes place

Explanation:

Leather gets hardened after tanning​ because mutual coagulation takes place.

Answer:

=2023.04 grams

Explanation:

Magnetite reacts with hydrogen to produce Iron metal and steam. Steam instead of water is produced as the reaction occurs at temperatures above the boiling point of water.

Fe₃O₄ + 4 H₂ → 3 Fe +4 H₂O

From the equation, 1 mole of Fe₃O₄ reacts with 4 moles of H₂.

69.76 grams of H₂ has the following number of moles.

Number of moles= mass/RAM

=69.76/2

=34.88 moles.

The reaction ratio of Fe₃O₄ to H₂ is 1:4

Thus number of moles of magnetite= (1×34.88)/4

=8.72 moles.

Mass= moles × RAM

=8.72 moles × (56×3+16×4)

=2023.04 grams

Answer:

electron pairs, i just did it on APEX

Explanation:

Final answer:

In VSEPR theory, the elements that are repelled are electron pairs, which include both bonding pairs and lone pairs, dictating the molecular geometry.

Explanation:

The Valence Shell Electron Pair Repulsion (VSEPR) theory predicts the arrangement of electron pairs around each central atom in a molecule. According to this theory, electron pairs are oriented to be as far apart as possible to minimize repulsions. Therefore, the elements that are repelled in VSEPR theory are D. Electron pairs. These include both bonding electron pairs (shared between atoms to make covalent bonds) and lone pairs (non-bonding electron pairs).

In VSEPR theory, the repulsion between electron pairs is a key factor in determining the geometric structure of molecules. For example, in a water molecule (H₂O), the two lone pairs on the oxygen force the hydrogen atoms to adopt a bent arrangement rather than a linear one.

Approximately 9.73 grams of H2O can be formed from 6.12g of NH3, using stoichiometric calculations and assuming a complete reaction with no limiting reactants.

In order to determine how many grams of H2O can be formed from 6.12g NH3, we must first apply the concept of the stoichiometry of chemical reactions. According to the balanced equation 4NH3(g) + 5O2(g) ➔ 4NO(g) + 6H2O(g), we understand that 4 moles of NH3 produce 6 moles of H2O

Firstly, we convert grams of NH3 to moles using its molar mass (about 17.03 g/mol). So, 6.12g of NH3 equates to around 0.36 moles.

Then, for each mole of NH3, we can form 1.5 moles of H2O (since 6 moles of H2O are produced by 4 moles of NH3). Thus, 0.36 moles of NH3 could potentially produce 0.54 moles of H2O. We can then convert these moles of H2O back into grams by multiplying by the molar mass of H2O, about 18.02g/mol. Therefore, approximately 9.73g of H2O could be produced from 6.12g of NH3, assuming a complete reaction and no limiting reactants.

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The mass of H2O that can be formed from 6.12 g of NH3 is approximately 9.71 g.

To determine the mass of H2O that can be formed from 6.12 g of NH3, we need to follow these steps:

 1. Calculate the moles of NH3 using its molar mass.

2. Use the stoichiometry of the balanced equation to find the moles of H2O that can be produced from the moles of NH3.

3. Convert the moles of H2O to grams using its molar mass.

Let's start with step 1:

 The molar mass of NH3 is [tex]14.01 g/mol (Nitrogen) + 1.008 g/mol (Hydrogen) * 3 = 17.034 g/mol.[/tex]

Now, we calculate the moles of NH3:

[tex]\[ \text{moles of NH3} = \frac{\text{mass of NH3}}{\text{molar mass of NH3}} = \frac{6.12 \text{ g}}{17.034 \text{ g/mol}} \approx 0.3593 \text{ mol} \][/tex]

Next, according to the balanced equation, 4 moles of NH3 produce 6 moles of H2O. Therefore, the moles of H2O produced from 0.3593 moles of NH3 are:

[tex]\[ \text{moles of H2O} = \text{moles of NH3} \times \frac{6 \text{ moles of H2O}}{4 \text{ moles of NH3}} = 0.3593 \text{ mol} \times \frac{6}{4} \approx 0.53895 \text{ mol} \][/tex]

Finally, we convert the moles of H2O to grams using the molar mass of H2O, which is 18.015 g/mol (2 * 1.008 g/mol for Hydrogen and 16.00 g/mol for Oxygen):

[tex]\[ \text{mass of H2O} = \text{moles of H2O} \times \text{molar mass of H2O} = 0.53895 \text{ mol} \times 18.015 \text{ g/mol} \approx 9.71 \text{ g} \][/tex]

Therefore, the mass of H2O that can be formed from 6.12 g of NH3 is approximately 9.71 g.

 The answer is: 9.71.

Answer:

Ultraviolet light.

Hope this helps!

Ultraviolet light has a wavelength of 350 nanometers. Therefore, the correct option is option D.

The length between identical spots between two succeeding waves is known as the wavelength, which is a feature of waves. The wavelength of a wave is indeed the distance among one wave's peak (or trough) and the next. In mathematics, the Greek symbol lambda () is used to denote wavelength.

The colour of light is determined by its wavelength, and the pitch of sound is determined by its wavelength. The visible spectrum of light has wavelengths between around 700 nm (red) and 400 nm (violet). The range of audible sound wavelengths is roughly 17 mm to 17 m. Compared to visible light, audible sound has far longer wavelengths. Ultraviolet light has a wavelength of 350 nanometers.

Therefore, the correct option is option D.

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Answer:

I think B..

Explanation:

It is the sharing of electrons from one atom to another .

Answer:

The answer is b: It is the sharing of electrons by overlapping orbitals

Explanation:

The ionic bong involves the exchange of electrons from one atom to another to keep eight particles in their outermost orbit. In this way the atoms become stable.  This happens between a metal, which losing electrons becomes a cation that now has a positive charge, and a non-metal, which accepting electrons becomes an anion that now has a negative charge. So the ionic bond is the electrostatic attraction between oppositely charged particle (cation and anion).

No chemical bond involves sharing neutrons between two nuclei. Chemical bonds occur between the electrons of atoms, which are found in the outer layer around the nuclei.

So, the correct answer is b: It is the sharing of electrons by overlapping orbitals.  This happens between two non-metallic elements.

the answer is electrons

Final answer:

The subatomic particle with the least mass is the electron, having a mass of about 0.00055 amu, which is significantly lighter than both the proton (1.0073 amu) and the neutron (1.0087 amu).

Explanation:

When comparing subatomic particles such as electrons, protons, and neutrons, the electron is the particle with the least mass. Despite all three being crucial components of an atom, an electron has an extremely small mass compared to protons or neutrons. Specifically, the mass of an electron is about 0.00055 amu (atomic mass units), whereas a proton has a mass of approximately 1.0073 amu, and a neutron has a mass of about 1.0087 amu.

Protons and neutrons, collectively known as nucleons, have masses that are nearly identical. However, the neutron is very slightly more massive. The vast difference in mass between electrons and nucleons (protons and neutrons) means that almost all the atomic mass is concentrated in the atom's nucleus, not in the electrons that orbit it.

Answer:

Inhibitor.

Explanation:

Answer:

(option D. with the proviso that the subscripts of propane's chemical formula must be corrected)

Explanation:

Propane is the saturated hydrocarbon, alkane, with chemical formula C₃H₈ or CH₃CH₂CH₃.

The complete combustion of the hydrocarbons yield carbon dioxide (CO₂) and water (H₂O).

The chemical equation that represents this combustion is:

Once you balance it, you get:

        Left side           Right side

C         3                          3

H         8                          4×2 = 8

O        5×2 = 10               3×2 + 4 = 10

That equation corresponds to the option D. of the list, with the proviso that the subscripts of propane's chemical formula must be corrected

Answer:

mechanical energy

Answer:

When the Keq value is large, the number representing [A]a[B]b must be smaller than the number representing [C]c[D]d. This relationship means that the products must be favored and that the mixture at equilibrium is largely products.

Explanation:

aA + bB ⇄ cC + dD,

Keq = ([C]^c x [D]^d)/([A]ᵃ[B]ᵇ),

So, When the Keq value is large, the number representing [A]a[B]b must be smaller than the number representing [C]c[D]d.

So, This relationship means that the products must be favored and that the mixture at equilibrium is largely products.

Answer:

1.smaller

2.products

3.products

Explanation:

When atoms combine to form molecules, a chemical change has occurred as there is a chemical reaction involved.

What is a chemical change?

Thus, a chemical change takes place when atoms combine to form molecules.

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Answer: option (A)

Explanation: The convection current is generates in the mantle due to the heat radiated from the core of the earth. Due to this convection current, the lithospheric plates moves as the upper part of the mantle known as the asthenosphere, is the region which is viscous in nature and drives the plates to move. This is a repeating cycle that constantly forces the plates to move.

Thus the correct answer is option (A).

Answer:

Mantle

Explanation:

Answer:

A. Hardness

Explanation:

Physical property is those that can be observed without changing the substance directly. This includes hardness, color, volume, etc.

Chemical property is observed by changing the chemical identity of the substance, for example, corrosion, oxidation, etc. Flammability, Reactivity, and Toxicity all fall under this category.

The physical property of a substance among the options is; Choice A: Hardness

The physical properties of a substance include properties which can be assessed about a substance without the substance going through any change.

On the other hand, chemical properties of a substance are properties which can only be assessed after the substance undergoes a chemical change..

Hence, Hardness is the only physical property of a substance among the options above.

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Answer:

yes with left over silver

Answer:

(A) 50 °C

Explanation:

Ideal gas law:

PV = nRT

If pressure is held constant, then:

V₁ / T₁ = V₂ / T₂

Substituting values:

(5.30 kL) / (12 + 273 K) = (6.00 kL) / T

T = 323 K

T = 50 °C

Answer:

Option (A) 50 °C

Explanation:

Thinking process:

Let the volume of the hot air be [tex]V_{1}[/tex] 5.30 k l = 5 300 l = 5.3 m³

The initial temperature will be 12 ° (12 + 273.15) = 285.15 K

The later volume, [tex]V_{2}[/tex] = 6 Kl = 6 000 l = 6 m³

The equation will be:

[tex]\frac{P_{1}V_{1} }{T_{1} } = \frac{P_{2}V_{2} }{T_{2} }[/tex]

If the pressure is the same, then:

[tex]\frac{5.3}{285.15} = \frac{6}{T_{2} }[/tex]

Solving for [tex]T_{2}[/tex] gives:

T₂ = 322.8

   = 49.66

   = 50°

Answer:

3626.76dm³

Explanation:

Given parameters:

Number of moles of Nitrogen in tank = 17moles

Temperature of the gas = 34°C

Pressure on the gas = 12000Pa

Unkown:

Volume of the tank, V =?

Converting the parameters to workable units:

We take the temperature from °C to Kelvin

K = 273 +  °C  = 273 + 34 = 307k

Taking the pressure in Pa to atm:

101325Pa = 1atm

12000Pa = 0.118atm

Solution:

To solve this problem, we employ the use of the ideal gas equation. The ideal gas law combines three gas laws which are the Boyle's law, Charles's law and the Avogadro's law.

            It is expressed as PV = nRT

The unknown is the Volume and we make it the subject of the formula

             V = [tex]\frac{nRT}{P}[/tex]

Where R is called the gas constant and it is given as 0.082atmdm³mol⁻¹K⁻¹

Therefore  V = [tex]\frac{17 x 0.082 x 307 }{0.118}[/tex] = 3626.76dm³

Answer: The volume of nitrogen will be 3614.15 L

Explanation:

To calculate the number of moles, we use the equation given by ideal gas equation:

[tex]PV=nRT[/tex]

Or,

[tex]PV=\frac{m}{M}RT[/tex]

where,

P = pressure of the gas = 12000 Pa = 12 kPa    (Conversion factor: 1 kPa = 1000 Pa)

V = Volume of gas = ?

n = number of moles of nitrogen = 17 moles

R = Gas constant = [tex]8.31\text{L kPa }mol^{-1}K^{-1}[/tex]

T = temperature of the gas = [tex]34^oC=[34+273]=307K[/tex]

Putting values in above equation, we get:

[tex]12kPa\times V=17mol\times 8.31\text{L kPa }mol^{-1}K^{-1}\times 307K\\\\V=3614.15L[/tex]

Hence, the volume of nitrogen will be 3614.15 L

Answer:

D.

Explanation:

It pushes the experimental results one way or another.  Less reliable.

Final answer:

In an experiment, bias refers to a factor that skews the results, pushing them in a particular direction and thus distorting the accuracy of the experiment's conclusions. Bias can stem from the experimental design, data collection, the researcher's subjective views, or systematic errors. Scientists work to minimize bias to ensure the validity and reliability of their results.

Explanation:

The term bias in an experiment refers to any factor that causes the results to deviate from the truth, distorting the conclusions drawn from the data. If we consider the given choices for what bias in an experiment is, the correct answer would be D. Something that pushes the experimental results one way or another. Experimental bias can come from a number of sources, such as the method of data collection, the experimental design, the researcher's expectations, or systemic errors. To maintain the integrity of an experiment, scientists aim to minimize bias by employing strategies such as random sampling, blinding, and standardization.

Biases can lead to a loss of validity, as they introduce systematic errors into the research that are not due to chance. By trying to disqualify the validity of their hypotheses, scientists work hard to remove bias from experiments, which strengthens the hypotheses that cannot be invalidated.

Bias can also come from subjective observations, which are based on personal feelings, as opposed to objective observations that are consistent regardless of who measures or observes them.

Answer:

I water molexule

Explanation:

equat8n= 2NO3 + h2O =2 HNO3

Final answer:

Upon balancing the redox reaction NO3- → NO, we find that two water molecules (2 H2O) are required for balancing the reaction, ensuring both mass and charge conservation.

Explanation:

The reaction provided, NO3- → NO, is an unbalanced redox reaction. Balancing redox reactions involves ensuring that both the number of atoms of each element and the charge are balanced on both sides of the equation. Let's focus on the nitrogen and oxygen atoms first, and then balance the hydrogen atoms and the charges. After balancing, the fully balanced equation becomes:

NO3- + 2 H+ + e- → NO + 2 H2O

To confirm the balance, verify that there are equal numbers of nitrogen atoms and oxygen atoms on each side of the equation, as well as that the total charge is balanced. Here we can see that there are the same number of nitrogen atoms (1 on each side) and oxygen atoms (3 on the left, 1 in NO, and 2 in the 2 H2O molecules), which means the number of atoms is balanced. Additionally, the total charge on each side is also the same (-1 on the left side with the nitrate ion and the 2 extra positive charges from the hydrogen ions equaling +1, and 0 on the right side with NO being neutral and water having no charge).

Therefore, two water molecules (2 H2O) are required to balance this redox reaction.

Answer:

One positive charge

Explanation:

In a neutral atom, the number of positive and negative particles are equal. This leaves the atom with a net charge of zero, 0.

When the number of protons in an atom is greater than the number of electrons, the atom becomes positively charged. When an atom loses an electron when a bond wants to form, it has a net positive charge.

The number of electrons lost or gained determines the charge.

Answer:

D

Explanation:

there is no explanation, I researched the topic

Hey there!:

Molarity of NaOH = 6 M or 6 mol/L

Volume of NaOH = 40 mL

Therefore , number of moles of NaOH:

40 mL  =( 6 mol / 1000 mL)*40=

6/ 1000 * 40 =>  0.24 moles of NaOH

Hope this helps!

The moles of NaOH will be 0.24 moles.

A mole would be defined as the quantity of a material that includes precisely 6.02214076 X 1023 of the particular chemical elementary entities.

Calculation of mole

Given data:

Volume = 40 ml

Molarity = 6M

Mole can be determined by using the formula:

Molarity = moles of solute / solution (L)

6 M = Moles of solute  ×1000/ 40

Moles of solute = 0.24 moles

Therefore, the moles of NaOH will be 0.24 moles.

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