help!!!! the relative formula mass (Mr) of sodium fluoride is 42. Use the correct answer frim the box to complete the sentence.​

Answer:

0.067M Fe(NO3)3

Explanation:

A stock solution is a concentrated solution that is diluted to prepare the solutions that you will use.

The volume of the stock solution is 3.0mL + 10.0mL + 17.0mL= 30.0mL.

The ratio between volume of the aliquot (10.0mL) and total volume (30.0mL) is called dilution factor, that is: 30.0mL / 10.0mL = 3

That means the Fe(NO3)3 is diluted 3 times. That means the molar concentration of the stock solution is:

0.200M / 3 =

There are approximately 6.022 × 10^23 atoms in 12 grams of Carbon-12 (12C).

The number of atoms in a given amount of a substance can be calculated using Avogadro's number, which represents the number of atoms or molecules in one mole of a substance. Avogadro's number is approximately 6.022 × 10^23.

Carbon-12 is a specific isotope of carbon, with an atomic mass of 12 atomic mass units (amu). One mole of Carbon-12 has a mass of 12 grams. Since one mole of any substance contains Avogadro's number of particles, in the case of Carbon-12, it contains 6.022 × 10^23 atoms.

Therefore, if we have 12 grams of Carbon-12, which is equal to one mole, we can conclude that there are approximately 6.022 × 10^23 atoms in this amount of Carbon-12.

In summary, 12 grams of Carbon-12 contains approximately 6.022 × 10^23 atoms. Avogadro's number allows us to relate the mass of a substance to the number of atoms or molecules it contains, providing a fundamental concept in chemistry and enabling us to quantify and understand the microscopic world of atoms and molecules.

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Answer:

explanation below

Explanation:

Dichlorodiphenyltrichloroethane, also known as DDT is a chemical compound that is found in insecticides. In 1972, the United States Environmental Protection Agency issued an order for the cancellation of requests for the chemical compound because it affects wildlife and pose risks to humans as well.  

From the question here, it was noted that the initial concentration was 22ppm 25years ago and so if it takes 7years to decay by half, the actual concentration in present day farmers could be calculated as follows;

25years ago  - 22ppm

18years ago  - 11ppm

11years ago – 5.5 ppm

4 years ago -  2.75ppm

Since 7yrs = 0.5

Then 4yrs will be [ [4/7] x 0.5] = 0.2857

Then if 0.5 = 2,

Then 0.2857 = [ [ 0.2857/0.5] x 2] = 1.1428

So present year concentration would then be [2.75ppm/1.1428] = 2.406ppm

Knowing the pH of a solution is not enough to determine its molarity, unless additional information about the chemical nature of the solution is provided. In the case of tomato juice, it is a complex mixture of various organic and inorganic compounds, including citric and malic acids, which contribute to its acidity.

The pH of a solution is defined as the negative logarithm (base 10) of the hydrogen ion concentration [H+] in moles per liter (M):

pH = -log[H+]

pH = -log(Ka / [H+])

[H+] = Ka / \(10^(^-^p^H^)\)

However, for a complex mixture like tomato juice, the concentration of hydrogen ions (and hence its molarity) is determined by the concentrations of all the acids present in the solution, which may not be the same for different samples of tomato juice.

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The steps of how plants get energy in the correct order is as follows:

Photosynthesis is the process by which plants and other photoautotrophs convert light energy into chemical energy.

Photosynthesis is carried out by the cells of green plants to synthesize their food in form of sugar powered by the energy from sunlight.

The cells in the leaf use the energy from the sun (light energy) and produce sugars (chemical energy). After which, the sugars are broken down to release energy for use by the cells in a process called cellular respiration.

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Answer:

Often animals use a strong flash of bioluminescence to scare off an impending predator. The bright signal can startle and distract the predator and cause confusion about the whereabouts of its target. From small copepods to the larger vampire squid, this tactic can be very useful in the deep-sea

Answer:

Q = -535 J.

Explanation:

Hello there!

In this case, according to the given information, it turns out possible for us to calculate the lost energy according to the following and generic heat equation:

\(Q=mC(T_F-T_i)\)

Thus, since the specific heat of iron is 0.450 in the SI units, we can plug in the mass and temperatures to obtain:

\(Q=28.3g*0.450\frac{J}{g\°C} (24.0\°C-66.0\°C)\\\\Q=-535J\)

Regards

Answer:

D

Explanation:

Answer:

False. Selenite (CaSO4.2H2O) when reacted with an acid will dissolve in it and there will be no effervescence.

Explanation:

we know that selenite is a crystalized form of gypsym and is transparent in nature and is formed when sulfate and calcium rich water evaporates and resulting hardness is 2 on Mohs scale.

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Answer:

B. Chlorine gas is yellow-green in color.

Answer: B is correct.

Explanation:

Answer A is a chemical change because of intense changes of color and expansion.

Answer C is a chemical change, as hydrogen and water are chemically bonding together.

Answer D is a chemical change because oxidation involves loss of electrons during a chemical reaction.

On the other hand, melting is a physical change. Therefore, answer B is the correct answer.

At equilibrium, the number of moles of \(Cl_2\) (g) will be 0.2025 mol.

1: Write the balanced chemical equation:

\(C_O\)(g) + \(Cl_2\)(g) ⟶ \(C_OCl_2\)(g)

2: Set up an ICE table to track the changes in moles of the substances involved in the reaction.

Initial:

\(C_O\)(g) = 0.3500 mol

\(Cl_2\)(g) = 0.05500 mol

\(C_OCl_2\)(g) = 0 mol

Change:

\(C_O\)(g) = -x

\(Cl_2\)(g) = -x

\(C_OCl_2\)(g) = +x

Equilibrium:

\(C_O\)(g) = 0.3500 - x mol

\(Cl_2\)(g) = 0.05500 - x mol

\(C_OCl_2\)(g) = x mol

3: Write the expression for the equilibrium constant (Kc) using the concentrations of the species involved:

Kc = [\(C_OCl_2\)(g)] / [\(C_O\)(g)] * [\(Cl_2\)(g)]

4: Substitute the given equilibrium constant (Kc) value into the expression:

1.2 x \(10^3\) = x / (0.3500 - x) * (0.05500 - x)

5: Solve the equation for x. Rearrange the equation to obtain a quadratic equation:

1.2 x \(10^3\) * (0.3500 - x) * (0.05500 - x) = x

6: Simplify and solve the quadratic equation. This can be done by multiplying out the terms, rearranging the equation to standard quadratic form, and then using the quadratic formula.

7: After solving the quadratic equation, you will find two possible values for x. However, since the number of moles cannot be negative, we discard the negative solution.

8: The positive value of x represents the number of moles of \(Cl_2\)(g) at equilibrium. Substitute the value of x into the expression for \(Cl_2\)(g):

\(Cl_2\)(g) = 0.05500 - x

9: Calculate the value of \(Cl_2\)(g) at equilibrium:

\(Cl_2\)(g) = 0.05500 - x

\(Cl_2\)(g) = 0.05500 - (positive value of x)

10: Calculate the final value of \(Cl_2\) (g) at equilibrium to get the answer.

Therefore, at equilibrium, the number of moles of \(Cl_2\) (g) will be 0.2025 mol.

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2) The heat capacity of aluminum is 219.44 J/mol.°C.

3) a) the experimental ΔHs of ice is -0.154 kJ/mol.

b) too high

Calculate the heat released by the aluminum:

q = mcΔT

where q = heat released, m = mass of aluminum, c = specific heat capacity of water and ΔT = change in temperature.

q = (24.7 g) (0.903 J/g°C) (100.0°C - 23.4°C)

q = 18643.26 J

Next, calculate the heat absorbed by the calorimeter:

q = mcΔT

q = (99.5 g + 24.7 g) (15.8 J/°C) (23.4°C - 19.5°C)

q = 4009.92 J

The heat released by the aluminum is equal to the heat absorbed by the calorimeter and water:

18643.26 J = 4009.92 J + q3

where q3 = heat absorbed by the water.

q3 = 14633.34 J

Calculate the molar heat capacity of aluminum:

Cp,m = q3 / (nΔT)

where Cp,m = molar heat capacity, n = number of moles of aluminum, and ΔT = change in temperature.

n = m / M

where m = mass of aluminum and M = molar mass of aluminum (26.98 g/mol).

n = 24.7 g / 26.98 g/mol

n = 0.916 mol

Cp,m = 14633.34 J / (0.916 mol * 76.6°C)

Cp,m = 219.44 J/mol.°C

Therefore, the heat capacity of aluminum is 219.44 J/mol.°C.

3) (a) To calculate the experimental ΔHs of ice, we first need to calculate the heat gained by the water and the heat lost by the ice during the process.

Heat gained by water = mass of water × specific heat capacity of water × change in temperature

= 100.0 g × 4.184 J/g·°C × (-20.1°C)

= -8,423.84 J

Heat lost by ice = mass of ice × heat of fusion of ice

= 25.6 g × 6.01 kJ/mol

= 154.496 J

Since the process is assumed to be adiabatic (no heat exchange with the surroundings), the heat gained by the water must be equal to the heat lost by the ice.

Thus, -8,423.84 J = 154.496 J = -8,269.344 J

The negative sign indicates that the process is exothermic. Therefore, the experimental ΔHs of ice is:

ΔHs = -154.496 J/mol = -0.154 kJ/mol

(b) If the student forgets to include the calorimeter term in the calculation, the calculated ΔHs of ice will be too high. This is because the heat absorbed by the calorimeter during the process is not accounted for, leading to an overestimation of the heat gained by the water and underestimation of the heat lost by the ice.

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Le Chatelier's principle: when a system is subjected to a stress, it will shift in a way to counteract the stress.

There a 4 types of changes that can occur:

Concentration Change: Altering the concentration of reactants or products, or changing the pressure (for reactions involving gases), can cause the system to shift to restore equilibrium. An increase in concentration of reactants causes a shift to products while a decrease causes a shift to reactants. For increase in products it shifts to reactants and for a decrease in product concentration it will shift towards the products. Essentially, shift away from addition and shift towards removal.

Temperature Change: Changing the temperature affects the equilibrium position differently depending on whether the reaction is exothermic or endothermic. Increasing the temperature of an endothermic reaction will make equilibrium shift to the reactants, if it is increased it will shift to the products. For an exothermic reaction, if temperature is increased, equilibrium will shift to the reactants and if temperature is decreased it will shift to the products.

Volume/Pressure Change: For reactions involving gases, altering the volume of the container or changing the pressure can impact the equilibrium position. Decreasing the volume/increasing the pressure favors the side with fewer moles of gas, while increasing the volume/decreasing the pressure favors the side with more moles of gas.

Addition/Removal of a Catalyst: The addition or removal of a catalyst does not change the equilibrium position but speeds up the attainment of equilibrium by increasing the reaction rate in both the forward and reverse directions.

According to this principle, an increase in temperature for an endothermic reaction will cause the equilibrium to shift towards he products. Therefore, b is correct.

Answer:

Br-CH2-CH(CH3)2-C(Cl)H-CH(CH3)2-CHO

Explanation:

The molecule has a total of 14 carbon atoms, 13 hydrogen atoms, and 1 bromine atom. The carbon atoms are arranged in a chain with a methyl group attached to the second carbon atom, a chlorine atom attached to the third carbon atom, and two methyl groups attached to the fourth carbon atom. The fifth carbon atom has a carbonyl group attached to it.

The molecule is an aldehyde, which means that it has a carbonyl group (C=O) at the end of the chain. The carbonyl group is polar, and the oxygen atom has a partial negative charge. The hydrogen atom has a partial positive charge. This polarity makes the aldehyde group susceptible to nucleophilic attack.

The bromine and chlorine atoms are both electrophilic, which means that they have a partial positive charge. This makes them susceptible to nucleophilic attack.

The methyl groups are non-polar and do not have any significant reactivity.

The molecule is a chiral molecule, which means that it has a mirror image that is not superimposable on itself. This is because the carbon atom with the carbonyl group is attached to four different groups.

The molecule is a liquid at room temperature and has a strong odor. It is used in a variety of products, including perfumes, flavorings, and plastics.

Answer:

C. Gases in the atmosphere prevent heat from escaping

Explanation:

Took one for the team and caught an L, C was the right answer

The greenhouse gases are known as the gases which absorb the infrared radiations and create greenhouse effect. Gases in the atmosphere prevent heat from escaping is the greenhouse effect. The correct option is C.

The process by which the radiations of the sun are absorbed by the green house gases and are not reflected back into the space is defined as the greenhouse effect. This insulates the earth and prevents it from freezing.

The green house effect increases the surface temperature of earth and also causes global warming.

Thus greenhouse effect is option C.

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Molecular polarity is important for life because it plays a crucial role in many biological processes.

Molecular polarity refers to the distribution of electrical charge within a molecule. It is a property that results from differences in the electronegativity of the atoms in a molecule.

Molecular polarity is important for life because many biological molecules, including proteins, DNA, and carbohydrates, are polar, meaning they have regions of positive and negative charge.

This allows them to interact with other polar molecules, such as water, through hydrogen bonding, which helps to stabilize their structures and maintain their functionalities.

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The specific heat is 0.134 J/gC

This is example in which energy (in the form of heat) is conserved.  Your metal is at a higher temperature than the water so it will lose heat, which we can calculate using q=mass x specific heat capacity x ΔT.  The heat is then transferred to the water.  One way to set up your calculation is: q metal + qH2O = 0

mass metal =  125 g

specific heat =  x

ΔT = 24 C - 288 C

mass water = 88 g

specific heat = 4.184 J/gC

ΔT = 24C-12C

125 g(x)(-264 C) + 88g(4.184J/gC)(12C)=0

-3300x + 4418.304 = 0

 x = 0.134 J/gC

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Answer:

24.31 g/mol.

Explanation:

moles =mass/molar mass

n=w/m

Answer:

4Al + 3O₂ →   2Al₂O₃

Explanation:

    4Al + 3O₂ →   2Al₂O₃

Only this reaction above obeys the law of conservation of mass. The others flout the rule.

The law of conservation of mass states that "matter is neither created nor destroyed in a chemical reaction but are simply transformed from one form to another".

By this law, the number of atoms on both sides of expression must be the same;

                                                    Number of atoms

Elements              Left hand side                                 Right hand side

  Al                                    4                                                     4

  O                                    6                                                    6

Answer:

d. tertiary and quaternary

Explanation:

Form or shape of protein can be understood by its structure. The structure of protein encompasses four levels of protein :

Hydrophobic Interactions refers to amino acids with non polar r group structure together on inside of protein, which leaves Hydrophobic amino acids outside to interact with surrounding water molecules.

These help to stabilise : D) Tertiary & Quaternary protein structures.

Answer: It rotates sideways due the extreme tilt of its axis

Uranus actually spins sideways on a axis so extreme that it is like us walking on walls

It rotates sideways due to the extreme tilt of its axis makes Uranus unique as a planet. Option D is correct.

A planet is a body present in the galaxy which rotates horizontally as well as vertically on the axis of orbits in fixed paths and the number of counts of them can be many numbers even more than stars

.

Now only 9 planets are discovered by science that are sun, venus, Uranus, Saturn, earth, mars, pluto mercury, and the moon. uranus rotate in the tilt mode at the axis of the rotation which makes it unique.

Therefore, Option D is correct. It rotates sideways due to the extreme tilt of its axis makes Uranus unique as a planet.

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Answer:53

Explanation:

Answer:

It travel's about 4,000 km through the Earth in 13 minutes.

Answer:

4,000 km is the correct answer!!!