a. Which date shows a waning crescent?

Answer: 190.9K

Explanation:

5.6(14) = 5(.0821)T  or  (5.6*14)/(5(.0821))

78.4 = 0.4105T

190.9K = T

Explanation:

The gamma ray photons make their arduous journey to the surface of the Sun, they are continuously absorbed by the solar plasma and re-emitted to lower frequencies. ... By the time they get to the surface, their frequencies are mostly only within the IR/visible light/UV spectrum. Nov28,2020

71. The broad, painless, pink-gray, wart-like infectious lesions that may develop on the vulva, perineum, or anus in syphilis are called "condyloma lata."

72. In suspected syphilis infection, the term RPR stands for "Rapid Plasma Reagin." It is a blood test used to screen for syphilis.

73. The recommended dosage of Benzathine Penicillin in an adult in Zambia may vary depending on the stage and severity of the syphilis infection. It is best to consult local guidelines or a healthcare professional for the specific recommended dosage in Zambia.

74. The recommended drug for the treatment of gonorrhea when using syndromic management may vary depending on local guidelines and antibiotic resistance patterns. Commonly used antibiotics include ceftriaxone in combination with azithromycin or doxycycline.

75. The causative organism for chancroid is called "Haemophilus ducreyi."

76. The commonest type of HIV is "HIV-1."

77. The assertive, problem-solving approach to the identification and treatment of the patient's problems is called "clinical decision-making."

78. A tumor arising from the cells producing melanin is also known as "melanoma."

79. The type of sound described as drum-like, loud, and empty quality felt over a gas-filled stomach, intestine, or pneumothorax during percussion is called "tympany."

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The following balanced chemical equation may be used to describe the interaction between aluminum (Al) and calcium nitrate (Ca(NO₃)₂):

2 Al + 3 Ca(NO₃)₂ → 2 Al(NO₃)3 + 3 Ca

Reactants are the chemicals that begin a chemical reaction, while products are the compounds that are created as a result of the reaction.

The substances that initiate a chemical reaction. Products are the substances that are created during the reaction. Compounds or elements can act as reactants and products.

Aluminium and calcium nitrate interact in this reaction to form aluminium nitrate (Al(NO₃)₃) and calcium (Ca), which are the end products.

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The expression 7.0x\(10^7\) ÷ 2.0x\(10^4\) can be expressed in proper scientific notation as 3.5x10^3.

To express the division 7.0x\(10^7\) ÷ 2.0x\(10^4\) in proper scientific notation, we need to perform the division and adjust the result to the appropriate format.

Dividing the numbers, we get:

7.0x\(10^7\) ÷ 2.0x\(10^4\)= 3.5x\(10^{(7-4)\)= 3.5x\(10^3\)

The result of the division is 3.5, and we adjust the exponent by subtracting the exponent of the divisor from the exponent of the dividend (7 - 4 = 3).

Therefore, the proper scientific notation representation of the division 7.0x\(10^7\) ÷ 2.0x\(10^4\) is 3.5x\(10^3\).

Scientific notation is a way to express numbers using a coefficient (in this case, 3.5) multiplied by a power of 10 (in this case, 10^3). It allows for more concise representation of very large or very small numbers.

In this case, the division resulted in a number that is smaller than the dividend and has a positive exponent, indicating a smaller magnitude compared to the original numbers. The coefficient represents the significant digits of the result, while the power of 10 represents the scale or magnitude of the number.

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The molar mass (formula weight) of carbon dioxide (CO2) is 44.01 g/mol.

At STP (Standard Temperature and Pressure), which is defined as 0°C (273.15 K) and 1 atm of pressure, 1 mole of any gas occupies 22.4 L of volume.

Now, we have 3.9 x 10^23 molecules of CO2:

- To find the number of moles, we divide the number of molecules by Avogadro's number:

n = N/Na = 3.9 x 10^23/6.022 x 10^23 = 0.648 moles

- To find the mass, we multiply the number of moles by the molar mass:

mass = n x M = 0.648 mol x 44.01 g/mol = 28.52 grams

Therefore, the mass of 3.9 x 10^23 molecules of carbon dioxide gas at STP is approximately 28.6 grams (option A).

Some acids can produce painful burns and damage tissues.

Acids can react violently with water and are harmful if water gets in the mouth eyes or near other aqueous solutions. Vapors from some acids are water soluble and can damage the eyes nasal passages throat, and lungs. Acid burns are usually felt immediately.

The short answer is that both acids and bases can be dangerous depending on pH and strength. For example, strong acids are more dangerous than weak bases and vice versa. Acids and bases are highly reactive with these chemicals and on contact form salts that destroy the original ingredients and damage the skin. Another major reason is that strong acids and strong bases quickly dissociate upon contact with water.

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ANSWER

Option A

EXPLANATION

Base is a substance that will reacts with an acid that to produce salt and water only.

Base is also a substance that produce hydroxide ions in an aqueous solution.

Below are the properties of a base

1. A base has a pH value greater than 7

2. A base is slippery to touch

3. A base has the ability to release hydroxide ions in aqueous solution.

4. A base has the ability to dissolve fats and oils.

Hence, base does not have sour taste which make option A the correct answer

Therefore, the correct answer is option A

The lowest and largest conversion factors are nanoliters and kiloliters, respectively. Among all the given options,  the correct option is option C.

A liquid, solid, or gas's volume is the amount of three-dimensional space it occupies. Although there are many different units that may be used to indicate volume, the most common ones are liters, m³, gallons, milliliters, teaspoons, as well as ounces.

Gases have a volume equal to the internal capacity of the container since they fill their containers to the brim. Containers with a designated volume or one whose interior form is known are frequently used to measure liquids. Measuring cups, graded cylinders, flasks, as well as beakers are a few examples of the tools used to quantify liquid volume.  3.0x10⁻¹²kiloliters represents the greatest volume.

Therefore, the correct option is option C.

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Answer:

Hi how are you doing today Jasmine

Answer:

[H₂SO₄] = 4.56 M

Explanation:

35.2 % by mass of H₂SO₄ means that in 100 g of solution, we have 35.2 grams of solute.

We convert the mass of solute to moles.

35.2 g / 98 g/mol = 0.359 moles

These moles are contained in 100 g of solution, so we use density to determine the volume.

1.27 g/mL = 100 g / volume

Volume = 100 g / 1.27 g/mL = 78.74 mL

Molarity is mmol /mL (either we can say, moles in 1L of solution).

We convert the moles to mmoles → 0.359 mol . 1000 = 359 mmoles

M = 359 mmoles/74.74 mL = 4.56 M

Answer:

Electron configuration is the structural arrangement notation of electrons in the shells or energy levels of an atom.

Explanation:

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Due to the latent heat of fusion, when a modest amount of heat is added, ice will transform into water without changing the temperature. Therefore, a portion of the ice may melt (but not all of it). The right answer is A.

The sun and stars are both powered by fusion. Fusion is the process by which two hydrogen atoms join, or fuse, to create a helium atom. Throughout the process, a portion of both the hydrogen's energy is converted into energy.

When multiple light nuclei combine by fusion, a heavy nucleus is produced. The process results in the production of energy because as the size of the single nucleus that forms is less than the sum of the masses of the two original nuclei. Every leftover mass is transformed into energy.

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ANSWER

Selenium has 34 protons

Answer:

Ans: 8.9 NaCl

Explanation:

Ocean water contains 3.5 nacl by mass how much salt can be obtained from 254 g of seawater

Question: Ocean water contains 3.5% NaCl by mass. How much salt can be obtained from 254g of seawater?

Answer:

A straight-chain alkane that has five carbon atoms, also known as pentane, differs from a cycloalkane that has five carbon atoms, also known as cyclopentane, in terms of their molecular structure and properties. Pentane has a linear, straight-chain structure, while cyclopentane has a ring-shaped structure. This difference in structure affects their physical and chemical properties. For example, pentane has a higher boiling point and lower melting point than cyclopentane due to the differences in the strength of the intermolecular forces between their molecules

Explanation:

Answer:

Explanation:

To calculate the value of the Ideal Gas Law Constant (R), we need to make some reasonable assumptions about the missing data.

First, let's assume that the atmospheric pressure is 1 atm. This is a reasonable assumption, as atmospheric pressure is typically close to 1 atm at sea level.

Next, we need to calculate the number of moles of gas produced by the reaction. We can do this by using the mass of potassium chlorate before and after the reaction. The initial mass of potassium chlorate was 191.3 mg, and the final mass was 52.9 mg. This means that 191.3 mg - 52.9 mg = 138.4 mg of potassium chlorate were converted into gas.

The molar mass of potassium chlorate is 122.55 g/mol, so 138.4 mg is equivalent to 138.4 mg / 122.55 g/mol = 1.13 x 10^-3 mol of potassium chlorate. Since the reaction produces two moles of gas for every mole of potassium chlorate, the total number of moles of gas produced by the reaction is 1.13 x 10^-3 mol x 2 = 2.27 x 10^-3 mol.

Finally, we need to calculate the volume of gas produced by the reaction. We can do this using the Ideal Gas Law, which states that the volume of a gas is equal to the number of moles of gas times the gas constant (R) divided by the pressure and temperature of the gas. Since we have already calculated the number of moles of gas and we have assumed the pressure to be 1 atm, we just need to calculate the temperature of the gas in Kelvin. The temperature of the gas in Celsius was 34.5 %€, so we can convert this to Kelvin by adding 273.15: 34.5 %€ + 273.15 = 307.65 K.

We also know that the volume of water displaced by the gas is 49.18 mL, and the height of the water column remaining is 5.8 cm. We can convert this to volume by using the formula for the volume of a cylinder: V = πr^2h, where V is the volume, r is the radius of the eudiometer, and h is the height of the water column remaining. Sincethe radius of the eudiometer is half the diameter, we can calculate the radius as 0.5 x 2.5 cm = 1.25 cm. Since the height of the water column remaining is 5.8 cm, the volume of the water displaced by the gas is π x 1.25^2 x 5.8 = 41.83 mL.

We can now use the Ideal Gas Law to calculate the volume of the gas produced by the reaction: V = nR/P * T = 2.27 x 10^-3 mol x 8.31 J/molK / 1 atm x 307.65 K = 0.721 L.

We can now use the Ideal Gas Law to calculate the value of R: R = PV/nT = 1 atm x 0.721 L / 2.27 x 10^-3 mol x 307.65 K = 8.31 J/molK.

Therefore, the value of the Ideal Gas Law Constant (R) is 8.31 J/molK.

In summary, to calculate the value of R, we made some reasonable assumptions about the missing data and used the Ideal Gas Law to calculate the volume of gas produced by the reaction. Using this information, we were able to calculate the value of R to be 8.31 J/molK.

1. Oxygen is a reactant needed for all combustion reactions.

2. The products of the complete combustion reaction of a hydrocarbon (compound containing carbon and hydrogen) are carbon dioxide and water.

3. Complete combustion takes place if the quantity of oxygen is sufficient.

4. Incomplete combustion takes place if the quantity of oxygen is insufficient.

5. Combustion is a exothermic change.

6. In a combustion reaction, oxygen is the oxidizer and the substance which burns is the fuel.

7. The lower the kindling temperature, the easier is the combustion.

8. If a substance burns at room temperature in the absence of a flame the combustion is said to be spontaneous.

9. Combustion reactions are accompanied by heat and light effect.

10. Combustion reactions don't take place at the same rate.

1)Oxygen is a reactant needed for all combustion reactions. Combustion reactions are chemical reactions that involve the rapid combination of a fuel (usually a hydrocarbon) with oxygen gas. Oxygen acts as the oxidizing agent, providing the necessary component for the reaction to occur. Without oxygen, combustion cannot take place.

2)The products of the complete combustion reaction of a hydrocarbon are carbon dioxide and water. In the presence of sufficient oxygen, hydrocarbons undergo complete combustion, resulting in the production of carbon dioxide (\(CO_2\)) and water (\(H_2O\)). This reaction releases a significant amount of energy in the form of heat and light.

3)Complete combustion takes place if the quantity of oxygen is sufficient. Complete combustion occurs when there is an adequate supply of oxygen available for the reaction. In this case, the fuel (hydrocarbon) reacts completely with oxygen, resulting in the formation of carbon dioxide and water as the only products

4)Incomplete combustion takes place if the quantity of oxygen is limited. In situations where there is insufficient oxygen available, incomplete combustion occurs. This leads to the formation of products such as carbon monoxide (CO) and carbon (soot) in addition to carbon dioxide and water. Incomplete combustion is less efficient and can release harmful pollutants into the environment.

5)Combustion is a chemical change. Combustion is classified as a chemical change because it involves the breaking and forming of chemical bonds between atoms and molecules. The reactants (fuel and oxygen) undergo a chemical reaction to produce new substances (products) with different properties, such as carbon dioxide and water. Heat and light are also typically released during combustion.

6)In a combustion reaction, oxygen is the oxidizer, and the substance that burns is the fuel or combustible material. Oxygen acts as the oxidizing agent, meaning it accepts electrons from the fuel, leading to the oxidation (burning) of the fuel. The fuel provides the carbon and hydrogen atoms that combine with oxygen to form carbon dioxide and water.

7)The lower the kindling temperature, the easier the combustion. The kindling temperature is the minimum temperature at which a substance can ignite and sustain combustion. If the kindling temperature is lower, it means that less heat is required to initiate the combustion process. Substances with lower kindling temperatures are more prone to catching fire and sustaining combustion.

8)If a substance burns at room temperature in the absence of a flame, the combustion is said to be spontaneous. Spontaneous combustion refers to the ignition and burning of a substance without the need for an external ignition source, such as a flame. It occurs when certain materials, under specific conditions, undergo self-heating and eventually reach their ignition temperature, leading to combustion.

9)Combustion reactions are accompanied by heat and light effects. Combustion reactions are highly exothermic, meaning they release a significant amount of heat energy. This energy is released in the form of heat and light, resulting in flames or glowing embers during combustion.

10)Combustion reactions don't take place at the same rate for all substances. The rate of combustion can vary depending on factors such as the nature of the fuel, the availability of oxygen, temperature, and pressure. Different substances have different combustion rates due to variations in their chemical properties and reactivity.

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To determine the original pressure of a 750 ml sample of helium (He) at 0 degrees Celsius, we can use the combined gas law, which relates the initial and final conditions of a gas sample. The combined gas law equation is:

(P1 × V1) / (T1) = (P2 × V2) / (T2)

Where:

P1 and P2 are the initial and final pressures, respectively.

V1 and V2 are the initial and final volumes, respectively.

T1 and T2 are the initial and final temperatures, respectively.

Let's assign the given values:

P1 = unknown (original pressure)

V1 = 750 ml (initial volume)

T1 = 0 degrees Celsius (initial temperature)

P2 = 2 atm (final pressure)

V2 = 500 ml (final volume)

T2 = 25 degrees Celsius (final temperature)

Before using the combined gas law equation, we need to convert the temperatures to Kelvin scale by adding 273.15 to both T1 and T2:

T1 = 0 + 273.15 = 273.15 K

T2 = 25 + 273.15 = 298.15 K

Now we can plug in the values into the combined gas law equation:

(P1 × 750 ml) / (273.15 K) = (2 atm × 500 ml) / (298.15 K)

To solve for P1, we can cross multiply and rearrange the equation:

P1 = (2 atm × 500 ml × 273.15 K) / (750 ml × 298.15 K)

P1 = 0.924 atm

Therefore, the original pressure of the 750 ml sample of helium at 0 degrees Celsius is approximately 0.924 atm.

Answer:

a because it help in protecting disease

From the information in the question, the formula unit of the salt is given as VCl.

The quantity of charge produced is obtained from;

Q = It

I = current (3 A), t = time (3600 s)

Q = 3 A × 3600 s

Q = 10800 C

Now we need to find the number of electrons transferred as follows;

51 g of Vanadium is deposited by 96500n C

5.70 g is deposited by 10800 C

5.70 × 96500n = 51 × 10800

n =  51 × 10800/5.70 × 96500

n = 1

The formula of the salt is VCl.

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To determine the total pressure of a gas mixture that contains oxygen (O2), you need to know the partial pressure of the oxygen gas and the partial pressures of the other gases in the mixture. The total pressure of a gas mixture is equal to the sum of the partial pressures of all the gases in the mixture. This is known as Dalton’s Law of Partial Pressures. Can you provide more information about the gas mixture, such as the partial pressures or mole fractions of the gases in the mixture?

Answer:yes

Explanation:

Both diamond and graphite are the allotropes of pure carbon (Carbon-12), they have different properties due to different types of arrangement of carbon atoms within their structures.

Diamonds have a strong three-dimensional network of carbon atoms while Graphites have a two-dimensional sheet-like structure. In a diamond, the network is formed because of the presence of covalent bonds between the carbon atoms. In graphite, bonds are generally due to weak Van der Waal's forces of attraction.

Therefore, diamonds are hard in nature while graphites are soft in nature. The molecules in diamonds are closely packed, as a result, they have high density. But in graphite, there is a large gap between molecules so they have low density.

As the diamonds have no presence of pi electrons they do not conduct electricity. But, there is the presence of pi electrons in graphite so they conduct electricity.

Therefore, the existence of isotopes does not explain the difference in properties between diamond and graphite

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Answer:

C. 6.99 moles

Explanation:

To convert molecules to moles we simply divide the given number of molecules by Avogadro's number, 6.022 x 10²³

Given number of molecules : 4.21 x 10^24

Number of moles : 4.21 x 10^24 / 6.022 x 10²³ = 6.99 moles ( rounded )

The answer is C

Answer:

This is the idea of spontaneous generation, an obsolete theory that states that living organisms can originate from inanimate objects. Other common examples of spontaneous generation were that dust creates fleas, maggots arise from rotting meat, and bread or wheat left in a dark corner produces mice

Explanation:

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Answer: Thus 663 J of heat  is released when 27.6 g \(PCl_3\) cools from 83.1 °C to 55.6 °C

Explanation:

The quantity of heat required to raise the temperature of a substance by one degree Celsius is called the specific heat capacity.

\(Q=m\times c\times \Delta T\)

Q = Heat released = ?

m = mass of substance = 27.6 g

C = specific heat capacity = \(0.874J/g^0C\)

Initial temperature= \(T_i\) = \(83.1^0C\)

Final temperature  = \(T_f\)  = \(55.6^0c\)

Change in temperature ,\(\Delta T=T_f-T_i=(55.6-83.1)^0C=-27.5^0C\)

Putting in the values, we get:

\(Q=27.6g\times 0.874J/g^0C\times -27.5^0C=-663J\)

As the value of q is negative, it means the heat has been released and it is 663J