A certain radioactive material has a half-life of 36 minutes. Starting with 10.00 grams of this material, how many grams will be left after 2 hours?

A) 1.00 grams
B) 1.5 × 10-4 grams
C) 3.33 grams
D) 0.25 gram

Final answer:

To make a 0.50 molal solution of NaCl with 750.0 g of water, 21.92 grams of sodium chloride must be dissolved in the water.

Explanation:

To calculate how many grams of sodium chloride (NaCl) are needed to make a 0.50 molal (m) solution with 750.0 g of water, we should understand the definition of molality. Molality is the number of moles of solute per kilogram of solvent. Therefore, a 0.50 molal solution of NaCl requires 0.50 moles of NaCl dissolved in each kilogram (1000 grams) of water. Since we have 750.0 g or 0.750 kg of water, we will adjust this proportionally.

First, calculate the moles of NaCl needed:

Next, convert the moles of NaCl to grams. The molar mass of NaCl is approximately 58.44 g/mol:

Therefore, 21.92 grams of sodium chloride must dissolve in 750.0 g of water to make a 0.50 molal solution.

Answer:

                                     Molarity  =  1.66 mol.L⁻¹

Explanation:

Monomers are generally small molecules that make up a long polymeric chain. The monomer for lipids is triglycerides.

A triglyceride is an ester consisting of three fatty acids and glycerol. Triglycerides are the main components of human body fat.

Lipids are made up of long chains of triglycerides.

Thus, the correct option is B.

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Answer:

Net ionic reaction: 2PO₄³⁻(aq) + 3Ca²⁺(aq) → Ca₃(PO₄)₂(s).

The net ionic equation for the reaction between aqueous sulfuric acid and aqueous sodium hydroxide is h+ (aq) + oh- (aq) → h2o (l). Here, the sodium ions are spectator ions and are thus not included in the net ionic equation.

The question asks about the net ionic equation for the reaction between aqueous sulfuric acid and aqueous sodium hydroxide. Remember, a net ionic equation includes only those components that undergo a change. Spectator ions are not included. In this case, the correct answer is (d) h+ (aq) + oh- (aq) → h2o (l). This equation represents the essential acid-base reaction that occurs. The sodium ion is a spectator ion in this reaction. Hence, it is not included in the net ionic equation.

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Final answer:

A dilute solution has a relatively small amount of solute compared to the solvent. Qualitative terms like 'dilute' and 'concentrated' describe the concentration of solutes in a solution, but for precise measurements, a quantitative expression of concentration is necessary.

Explanation:

A solution with a relatively low amount of solute is referred to as a dilute solution. This term contrasts with a concentrated solution, which contains a larger quantity of solute. In a dilute solution, the solute is present in a lower concentration compared to the solvent, which is the substance present in a higher concentration.

When discussing the concentration of solutions, it is essential to express it quantitatively for precision. However, qualitative descriptors such as 'dilute' and 'concentrated' are commonly used. The meaning of these terms can vary depending on several factors, such as the nature of the solute and solvent, as well as the context in which they are used.

For example, a solution containing 1 gram of salt in 1 liter of water is more dilute than a solution containing 10 grams of salt in the same amount of water. The latter would be considered more concentrated. Both terms are relative and describe the amount of solute dissolved in a solvent without precisely quantifying the concentration.

ANSWER: C temperature of the gas

Answer:

(C) The temperature of gas

Explanation:

It's correct for Plato

Answer:

c. Some unstable materials decay radioactively into other unstable materials.

Explanation:

got it correct on edg

Answer:

the options are

2, 3, 1

1, 3, 2

4, 3, 2

3, 2, 3

when balancing equation the masses should be balanced. In other words the same number of atoms of the same element should be on either side of the equation

the balanced equation for the oxidation of aluminium is as follows

4Al + 3O₂ ---> 2Al₂O₃

coefficients are the numbers in front of the respective compounds.

the coefficients in the correct sequence are 4,3 and 2

answer is 4, 3, 2

Answer : The number of moles of carbon sulfide produced are, 1.18 moles.

Explanation : Given,

Moles of carbon = 5.9 moles

The balanced chemical reaction is:

[tex]5C+2SO_2\rightarrow CS_2+4CO[/tex]

From the balanced chemical reaction we conclude that,

As, 5 moles of carbon react to give 1 mole of carbon sulfide

So, 5.9 moles of carbon react to give [tex]\frac{5.9}{5}=1.18[/tex] mole of carbon sulfide

Thus, the number of moles of carbon sulfide produced are, 1.18 moles.

Using Gay-Lussac's Law, we calculate that when the temperature of a gas increases from 320 K to 450 K, the pressure of the gas will increase from 1.5 atm to 2.1 atm, assuming the volume and the amount of gas remain constant.

To answer the question, we need to use the concept in physics called Gay-Lussac's Law. This law states that the pressure of a given amount of gas held at a constant volume is directly proportional to the Kelvin temperature. It's also important to remember that when we're dealing with gases, temperatures have to be in Kelvin for our calculations to work.

Given that, we know that the initial pressure (P1) is 1.5 atm, the initial temperature (T1) is 320K, and the final temperature (T2) is 450K. We want to find the final pressure (P2). According to Gay-Lussac's law, this can be calculated using the following equation: P1/T1 = P2/T2.

Thus, P2 = P1 * T2 / T1 = 1.5 atm * 450K / 320K = 2.1 atm.

So, the gas pressure will be 2.1 atm when the temperature increases from 320 K to 450 K, assuming that the volume and the amount of gas remain constant.

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Answer: 127 g

Explanation:

Answer: iron (III) chloride is the excess reactant in the reaction.

Explanation:

i just did the assignment

Answer:

For 3: The total mass change of the reaction is [tex]4.255\times 10^{3}kg[/tex]

For 4: The mass defect is [tex]0.911\times 10^{-27}kg[/tex] and energy equivalent to this mass is [tex]8.199\times 10^{-14}kJ[/tex]

For 5: The equivalent mass of the reaction is [tex]1.5755\times 10^{-11}kg[/tex]

Explanation:

To calculate the mass change of the reaction for given energy released, we use Einstein's equation:

[tex]E=\Delta mc^2[/tex]

E = Energy released = [tex]3.83\times 10^{-12}J[/tex]

[tex]\Delta m[/tex] = mass change = ?

c = speed of light = [tex]3\times 10^8m/s[/tex]

Putting values in above equation, we get:

[tex]3.83\times 10^{-12}Kgm^2/s^2=\Delta m\times (3\times 10^8m/s)^2\\\\\Delta m=4.255\times 10^3kg[/tex]

Hence, the total mass change of the reaction is [tex]4.255\times 10^{3}kg[/tex]

For the given isotopic representation:  [tex]_{27}^{60}\textrm{Co}[/tex]

Atomic number = Number of protons = 27

Mass number = 60

Number of neutrons = Mass number - Atomic number = 60 - 27 = 33

To calculate the mass defect of the nucleus, we use the equation:

[tex]\Delta m=[(n_p\times m_p)+(n_n\times m_n)+]-M[/tex]

where,

[tex]n_p[/tex] = number of protons  = 27

[tex]m_p[/tex] = mass of one proton  = 1.00728 amu

[tex]n_n[/tex] = number of neutrons  = 33

[tex]m_n[/tex] = mass of one neutron = 1.00867 amu

M = Nuclear mass number = 59.9338 amu

Putting values in above equation, we get:

[tex]\Delta m=[(27\times 1.00728)+(33\times 1.00867)]-[59.9338]\\\\\Delta m=0.54887amu[/tex]

Converting the value of amu into kilograms, we use the conversion factor:

[tex]1amu=1.66\times 10^{-27}kg[/tex]

So, [tex]0.54887amu=0.54887\times 1.66\times 10^{-27}kg=0.911\times 10^{-27}kg[/tex]

To calculate the equivalent energy, we use the equation:

[tex]E=\Delta mc^2[/tex]

E = Energy released = ?

[tex]\Delta m[/tex] = mass change = [tex]0.911\times 10^{-27}kg[/tex]

c = speed of light = [tex]3\times 10^8m/s[/tex]

Putting values in above equation, we get:

[tex]E=(0.911\times 10^{-27}kg)\times (3\times 10^8m/s)^2\\\\E=8.199\times 10^{-11}J[/tex]

Converting this into kilojoules, we use the conversion factor:

1 kJ = 1000 J

So, [tex]8.199\times 10^{-11}J=8.199\times 10^{-14}kJ[/tex]

Hence, the mass defect is [tex]0.911\times 10^{-27}kg[/tex] and energy equivalent to this mass is [tex]8.199\times 10^{-14}kJ[/tex]

For the given chemical reaction:

[tex]C_2H_5OH(l)+3O_2(g)\rightarrow 2CO_2(g)+3H_2O(l);\Delta H=-1418kJ/mol[/tex]

To calculate the equivalent mass of the reaction for given energy released, we use Einstein's equation:

[tex]E=\Delta mc^2[/tex]

E = Energy released = [tex]1418kJ=1418\times 10^3J[/tex]

[tex]\Delta m[/tex] = mass change = ?

c = speed of light = [tex]3\times 10^8m/s[/tex]

Putting values in above equation, we get:

[tex]1418\times 10^{3}Kgm^2/s^2=\Delta m\times (3\times 10^8m/s)^2\\\\\Delta m=1.5755\times 10^{-11}kg[/tex]

Hence, the equivalent mass of the reaction is [tex]1.5755\times 10^{-11}kg[/tex]

Answer: Latent Heat of Vaporization

Final answer:

Aluminum hydroxide can be safely ingested in small amounts as it's used in antacids, while sodium hydroxide, calcium hydroxide, and ammonia have various uses but are not safe to ingest in their industrial forms.

Explanation:

The student is asking about which bases can be safely ingested. Among the options given, aluminum hydroxide is a compound that can be ingested safely in small amounts, as it is often used in antacids to combat excess stomach acid. Sodium hydroxide, commonly found in drain cleaner, and calcium hydroxide, though it is used in food processing, must be consumed in very limited amounts because of their high reactivity and potential for causing harm. Ammonia is a weak base and is used in cleaning products; it should not be ingested due to its toxicity. It is important to note that while some bases can be ingested in medicinal or food-grade forms, their industrial counterparts used in cleaning and other products can be harmful and should not be ingested.

Answer: D: By decreasing the activation energy

Explanation: A catalyst is a substance which increases the rate of a reaction by taking the reaction through a different path which involves lower activation energy and thus more molecules can cross the energy barrier and convert to products.

Activation energy is the extra energy that must be supplied to reactants in order to cross the energy barrier and thus convert to products.

The catalyst itself does not take part in the chemical reaction and is regenerated as such at the end.

Answer:

The nucleus of an atom of U-235 splits, resulting in two smaller fragments and the release of a large amount of energy

Explanation:

In the fission reaction U-235 absorbs one neutron and breaks into two new atoms (also known as  fission fragments) and three neutrons with the release of massive amount of energy.  

The nuclear fission reaction is as follows:

¹₀n + ²³⁵₉₂U → ¹⁴¹₅₆Ba + ⁹²₃₉Kr + 3 ¹₀n

U-235 has a half life of 703.8 million years. In the fission reaction massive amount of energy 202.5 MeV is released.  

Final answer:

The characteristics of Wassily Kandinsky's Improvisation 31 show his innovative use of color and line for their own sake, reflecting his move towards pure abstraction and exploring the emotional and spiritual qualities of art.

Explanation:

A characteristic of Wassily Kandinsky's Improvisation 31 is the use of color and line for their own sake, not to represent something specific. Kandinsky aimed to create a sense of rhythm and staccato in the painting, infusing it with musicality through abstract elements.

Improvisation 31, like many of Kandinsky's works, reflects his move towards pure abstraction and his interest in the spiritual and emotional aspects of art. The painting is a representation of the Expressionist movement in early 20th-century art, seeking to convey inner emotions rather than outward impressions.

Impressionism 31 showcases Kandinsky's innovative approach to art, breaking away from traditional representation and embracing the freedom of abstract expression, marking a significant shift in the art world. Through his use of color, line, and form, Kandinsky creates a visually dynamic and emotionally evocative piece that invites viewers to explore the depths of their subconscious.

Explanation:

According to the mole concept, there are [tex]6.022 \times 10^{23}[/tex] atoms or molecules present in 1 mole.

As, it is given that mass of ethyne is 84.3 g. Hence, calculate its number of moles as follows.

          No. of moles = [tex]\frac{mass}{\text{molar mass}}[/tex]

                                 = [tex]\frac{84.3 g}{26.04 g/mol}[/tex]

                                 = 3.24 mol

Therefore, calculate number of ethyne molecules as follows.

                 [tex]3.24 mol \times 6.022 \times 10^{23}[/tex] atoms

                    = [tex]19.51 \times 10^{23}[/tex] atoms

Thus, we can conclude that there are [tex]19.51 \times 10^{23}[/tex] atoms in 84.3 grams of ethyne.

Approximately 200.6 grams of Aluminum will be produced from the electrolysis of molten AlCl3 for 3.25 hours with an electrical current of 15.0 A, as determined through application of Faraday's law of electrolysis.

In order to determine the number of grams of aluminum produced from electrolysis of molten AlCl3, we need to use Faraday's law of electrolysis.

Faraday's law states that the amount of substance produced at an electrode during electrolysis is directly proportional to the number of moles of electrons (or amount of electrical charge) transferred at that electrode. The charge Q in coulombs (C) can be calculated using the formula Q = It, where I is the current in amperes (A) and t is the time in seconds.

For this scenario, we know that the current I is 15.0 A and the time t is 3.25 hours, which needs to be converted to seconds for the equation to work properly (3.25 hr × 3600 s/hr = 11700 s). Hence, Q = 15.0 A × 11700 s = 175500 C.

The quantity of a substance produced in an electrolytic cell is given by the equation  m = Q × M / F × n, where M is the molar mass of the substance, F is Faraday's constant (~96485 C/mol), and n is the number of electrons transferred per formula unit of the substance. In this case, M = 26.98 g/mol for Al, n = 3 for Al3+, so m = 175500 C × 26.98 g/mol / (96485 C/mol × 3) = 200.6 g

Therefore, approximately 200.6 g of Aluminum will be produced from the electrolysis of AlCl3 in 3.25 hours with an electrical current of 15.0 A.

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