Answer:
I - 131 is the correct answer.
I - 131 is the only naturally occuring radioactive isotope among these four options.
Explanation:
Np - 239 - Neptunium is also considered as an artificial element,as only trace amounts of it are found in nature.
And Np - 239 is not a naturally occuring radioactive isotope but it is synthesized artificially.
No - This is an artificial element.That means its not found in nature. Hence all its isotopes are also synthesized artificially.
Cm - This is also an artificial element and all its isotopes are also synthesized artificially.
Np - 239,No - 254,Cm - 242 are radioactive isotopes but they are not naturally occuring radioactive isotopes. But these three are artificially made radioactive isotopes.
And Iodine - 131 is the only naturally occuring radioisotope among these.
A moving car powered by gasoline provides evidence of _____. chemical energy being converted into work gasoline being destroyed while energy is being created an endothermic reaction taking place potential energy being destroyed and heat energy being created
calculate the molecular weight of chalk.write any two advantages of mandeleev's periodic table?
Final answer:
To calculate the molecular weight of chalk (calcium carbonate), you need to find the atomic masses of each element in the compound and add them together. Mendeleev's periodic table provided a clear and systematic framework for understanding the behavior of elements and identifying relationships and patterns among them.
Explanation:
To calculate the molecular weight of chalk (calcium carbonate), we need to find the atomic masses of each element in the compound and add them together. The molecular formula of calcium carbonate is CaCO₃. The atomic masses of calcium, carbon, and oxygen are approximately 40.08 g/mol, 12.01 g/mol, and 16.00 g/mol, respectively. So, to calculate the molecular weight, we multiply the atomic mass of calcium by one, the atomic mass of carbon by one, and the atomic mass of oxygen by three (since there are three oxygen atoms in the formula).
Advantages of Mendeleev's periodic table include:
Organizing the elements based on their chemical properties provided a clear and systematic framework for understanding the behavior of elements and predicting the properties of undiscovered elements. Mendeleev's periodic table allowed for the identification of relationships and patterns among elements, which led to a deeper understanding of atomic structure and bonding.What happens to a ionic compound when it has fully been dissolved in water?
Suppose you have a spherical balloon filled with air at room temperature and 1.0 atm pressure; its radius is 17 cm. You take the balloon in an airplane, where the pressure is 0.87 atm. If the temperature is unchanged, what's the balloon's new radius?,
Answer:
The new radius of the balloon is 17.8 cm.
Explanation:
Initial pressure of the air in the balloon =[tex]P_1[/tex] 1.0 atm
Radius of the balloon ,r= 17 cm
Volume of the spherical volume balloon = [tex]V_1=\frac{4}{3}\pi r^3[/tex]
Final pressure of the air in balloon =[tex]P_2[/tex]=0.87 atm
Radius of the balloon be R
Volume of the balloon be = [tex]V_2=\frac{4}{3}\pi R^3[/tex]
New radius of the balloon= R
According Boyle's Law:
[tex]P_1V_1=P_2V_2[/tex]
[tex]1.0 atm\times \frac{4}{3}\pi r^3=0.87 atm\times \frac{4}{3}\pi R^3[/tex]
R =17.80 cm
The new radius of the balloon is 17.8 cm.
Why did the candles stop burning when the students placed glass jars over them?
Candles burn because it gets enough oxygen from open space. When the jar is closed it didn't get oxygen to burn. Thus, the candle will distinguish.
What is oxygen?Oxygen is 8th element in periodic table. It is the most abundant element in earth crests. Oxygen is precious because, it is used to respire by all livings things.
Biospheres is interconnected with the atmosphere. The changes in atmosphere affects the biosphere. Thus, the composition of gases will definitely affects the living in biosphere.
The gas which burn in atmosphere is hydrogen. But the gas which helps to burn is oxygen. Substances get oxidised when reacting with oxygen. Thus combustion of matter is aided by oxygen.
Open air oxidation aids substance to burn. Thus, the burning of candles is aided with the circulation oxygen gases. Hence, when the jar closes the air circulation gets off and it will stop burning.
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Answer:
Oxygen is needed to maintain this type of combustion reaction. The jars prevent oxygen in the surrounding air from reaching the flames, so the flames go out.
Explanation:
This is the correct answer
Which statement describes a property of covalent compounds?
They have a high boiling point because of strong intermolecular forces.
They have a low boiling point because of weak intermolecular forces.
They have a low melting point because of strong intermolecular forces.
They have a high melting point because of weak intermolecular forces.
19) What is the molarity of a KOH solution if 200 ml of the solution contains 0.6 moles KOH?
Answer: 3M
Explanation: Molarity : It is defined as the number of moles of solute present in one liter of solution.
Formula used :
[tex]Molarity=\frac{n\times 1000}{V_s}[/tex]
where,
n = moles of solute [tex]KOH[/tex] = 0.6 moles
[tex]V_s[/tex] = volume of solution in ml= 200 ml
Now put all the given values in the formula of molarity, we get
[tex]Molarity=\frac{0.6moles\times 1000}{200ml}=3mole/L[/tex]
Therefore, the molarity of solution will be 3M.
Answer:
3 moles
Explanation:
200 ml is 1/5 of a liter, so the answer is five times the number of moles present in the solution. 0.6 moles/0.2 liter = x moles/1.0 liter. Solving for x gives 0.2 x = 0.6 or x = 3.0 M.
What is the only type of invertebrate that may be smarter than some vertebrates?
a.
Ants
c.
Squid
b.
Octopi
d.
Dolphins
The octopus is recognized as the invertebrate that may be smarter than some vertebrates, due to its well-developed brain and complex behaviors within the class Cephalopoda. Option C is correct.
The only type of invertebrate that may be smarter than some vertebrates is the octopus. This remarkable creature, along with its relatives in the class Cephalopoda, which includes both the octopus and the squid, possess highly developed brains.
Cephalopods are considered to be amongst the most intelligent invertebrates, with abilities to change color, texture, and body shape for camouflage, along with the power of 'disappearing' in a puff of ink when threatened. They have large brain-to-body size ratios, complex nervous systems, and display behaviors indicative of high cognitive functioning. Their intelligence makes them formidable predators in the marine ecosystem.
Hence, C. is the correct option.
The complete question is:
What is the only type of invertebrate that may be smarter than some vertebrates?
a. Ants
b. Squid
c. Octopus
d. Dolphins
Net-ionic equation for hydrolysis of ZnCl2
The net-ionic equation for hydrolysis of ZnCl₂ in water typically produces zinc hydroxide and hydrogen ions, but the equation provided incorrectly represents a neutralization reaction.
Explanation:The net-ionic equation for the hydrolysis of zinc chloride (ZnCl₂) in water involves the hydrolysis reaction where the Zn²+ cation reacts with water to produce a weak acid and the Zn(OH)₂ solid as the product.
However, the net-ionic equation presented here is incorrect for hydrolysis, as it represents a neutralization reaction.
In hydrolysis, the relevant products would involve zinc hydroxide as a precipitate and hydrogen ions or hydronium ions depending on the pH of the solution.
When native prairie soils are brought under cultivation, the fraction of soil organic carbon which disappears most quickly is the passive fraction?
Answer:
The given statement is false.
Explanation:
When the prairie soils are brought under cultivation, the fraction of soil organic compound carbon that disappears most briskly is not the passive fraction. Humus is considered as the passive fraction of soil organic matter. It is a complex and dark amalgamation of organic components, which have been modified substantially from the native form over time, and it also comprises other components that have been produced by soil organisms.
Prairie soils are the dark fertile soils, which are produced due to the gathering of organic matter generated by dense root systems of prairie grasses. Most of these soils are witnessed in temperate regions with varying environments. They are considered as the most fertile soils found on the planet and the majority of the products used by humans comes from these kinds of soils.
Compare the evaporation of a contained liquid with that of an uncontained liquid.
Answer: all other conditions equal, the rate evaporation of a contained liquid will be slower than the rate of evaporation of an uncontained liquid.
Justification:
1) The rate of evaporation increases as the surface area of the liquid (relative to the whole content) increases. This is, the greater the surface is the faster the evaporation.
2) That is so because the higher the surface of the liquid the more the number of particles in the liquid that are in contact with the surrounding air and so the more the particles will escape from the liquid to the air (which is what evaporation is).
3) A liquid contained will take the form of the container, so part of the liquid wil remain below the surface, while an uncontained liquid will spread all over the surface and so pratically all the liquid is in contact witht the air surrounding it.
How much energy is required to ionize a hydrogen atom in its ground?
The mass in grams of 2.75 x 1021atoms of Li is.
a.
0.3017 g
c.
3.017 g
b.
0.0317 g
d.
0.00317 g
Final answer:
To find the mass of 2.75 x 10²¹atoms of Lithium, we first calculate the number of moles of Li and then use its molar mass. The mass is found to be 0.0317 g, which is option (b).
Explanation:
The question asks for the mass in grams of 2.75 x 10²¹ atoms of Lithium (Li). First, we need to calculate the number of moles of Li this number of atoms represents. Knowing that one mole contains 6.02 x 10²³atoms, the number of moles is calculated as follows:
(2.75 x 10²¹ atoms) / (6.02 x 10²³atoms/mol) = 4.57 x 10⁻³ mol
Next, using the molar mass of Li, which is 6.94 g/mol, we can find the mass of Li:
(4.57 x 10⁻³ mol) x (6.94 g/mol) = 0.0317 g
Therefore, the mass of 2.75 x 10²¹ atoms of Li is 0.0317 g, which corresponds to option (b).
Which of the following statements is true?
Question 4 options:
In an endothermic reaction, the energy of the products is the same as the energy of the reactants.
In an exothermic reaction, the energy of the products is less than the energy of the reactants.
In an exothermic reaction, the energy of the products is the same as the energy of the reactants.
In an endothermic reaction, the energy of the products is less than the energy of the reactants.
give an explanaintion if you can
How do i check if a molecule is coplanar?
To check whether a molecule is coplanar, look for a plane of symmetry, which indicates that all atoms lie within the same plane. Models or visualization software can assist with this task. It is especially important to consider different conformations of the molecule as it may exhibit coplanarity only in certain orientations.
Checking if a molecule is coplanar involves determining whether all of its atoms reside in the same geometric plane. To assess coplanarity, a method often used is looking for a plane of symmetry. This is a hypothetical plane that bisects the molecule such that one half is the mirror image of the other half. If all atoms lie on or symmetrically around this plane, the molecule is planar. In a coplanar molecule, the molecule is cyclic, meaning it forms a ring, and planar since all atoms lie within the same plane.
For molecules with known stereocenters, which are atoms—typically carbons—bonded to four different substituents, the presence of multiple stereocenters can sometimes suggest a lack of coplanarity; however, when these stereocenters are arranged symmetrically (as in meso compounds), the molecule can still exhibit coplanarity. Using models or software to visualize the three-dimensional structure of the molecule can assist in this process, especially when manual inspection on paper is challenging.
If you cannot easily visualize the symmetry in a molecule, constructing a three-dimensional model may help to identify the presence of a plane of symmetry—or lack thereof. It's important to consider that some molecules may only demonstrate coplanarity in certain conformations, so examining the molecule in different orientations could be necessary for an accurate determination.
Which of the answer choices lists a true statement about ionic compounds?
1. They are formed by atoms that have the same number of valence electrons.
2. They are formed by ions that have the same charge.
3. They are formed by ions that have the opposite charges.
4. They are formed by atoms that have the same number of protons.
Answer:
3. They are formed by ions that have the opposite charges.
Explanation:
Ionic compounds are formed when two oppositely charged ions react. Ionic bonds are formed when an atom has tendency to loose its valence electron/electrons and another atom has tendency to accept them. All the atoms on this earth want to be stable but they can be stable only when they have stable electronic configuration. Some atoms like noble gases have stable electronic configuration already so they don't need to react with any other atom of any other element but others do not have stable electronic configuration and in order to achieve this stable electronic configuration they need to react with atoms of other elements through various kind of bonds/interactions like ionic bond.
An example of ionic bond is interaction between magnesium ion (Mg2+) and chloride (Cl-) to form magnesium chloride (MgCl2).
Apart from ionic bonds there are other type of interactions too like covalent bonds, hydrogen bonds, hydrophobic interactions etc.
For a given sample of ch3oh, the enthalpy change during the reaction is 82.3 kj . how many grams of methane gas are produced?
To find the number of grams of methane gas produced, use the enthalpy change and stoichiometry of the reaction. Assuming the reaction is the combustion of methane, calculate the moles of methane using the enthalpy change and convert it to grams.
Explanation:To determine the number of grams of methane gas produced, we need to use the enthalpy change and stoichiometry of the reaction. From the given information, we know that the enthalpy change is 82.3 kJ. Since the reaction is not specified, we'll assume it's the combustion of methane:
CH4 + 2O2 -> CO2 + 2H2O
The stoichiometry of the reaction tells us that for every 1 mol of methane, we produce 1 mol of CO2. Therefore, the number of grams of methane can be calculated as follows:
Convert the enthalpy change from kJ to J: 82.3 kJ = 82,300 J Calculate the moles of methane using the enthalpy change: 82,300 J / -802 kJ/mol = -102.62 mol Convert the moles of methane to grams using the molar mass of methane (16 g/mol): -102.62 mol * 16 g/mol = -1642.96 g The negative sign indicates that the reaction is exothermic, meaning heat is released.Learn more about Enthalpy change during a reaction here:
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Given an enthalpy change of 82.3 kJ during a reaction involving methanol (CH3OH), approximately 1.47 grams of methane (CH4) would be produced. This is derived by applying the principles of stoichiometric calculations and enthalpy changes, and considering the exothermic nature of the combustion reaction of methane.
Explanation:To answer your question about how many grams of methane gas are produced given a sample of ch3oh (methanol) and an enthalpy change of 82.3 kJ, we need to apply the principles of stoichiometric calculations and enthalpy changes. In this problem, we can use a similar approach to what we would use in a stoichiometry problem.
First, it's important to note that the combustion reaction of methane (CH₄) is exothermic, meaning it releases energy. Specifically, the combustion of 1 mole of methane releases approximately 890.4 kJ of energy, as shown by the chemical reaction:
CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(g) + 890.4 kJ
Given that the enthalpy change is 82.3 kJ, we can calculate the amount of methane combusted. We can convert the energy change from kJ to mol, using the known energy/reaction ratio of 890.4 kJ/mol, which gives us approximately 0.092 mol of CH₄. Subsequently, we can convert moles into grams using the molar mass of methane (16 g/mol). This gives the final answer of approximately 1.47 grams of methane.
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This is a systematic method of naming chemical compounds. This creates an unambiguous and consistent name for any chemical compound throughout the world.
If you start with 10.0 grams of lithium hydroxide how many grams of lithium bromide will be produced
Of the bonds c-c, cc, and c≡c, the c-c bond is ___
Answer:
weakest and the longest
A 55.0-g piece of copper wire is heated, and the temperature of the wire changes from 19.0°C to 86.0°C. The amount of heat absorbed is 343 cal. What is the specific heat of copper? Show your work.
What is the layer of Earth's atmosphere that has the coldest temperature range?
A 130.0−mL sample of a solution that is 3.0×10−3M in AgNO3 is mixed with a 225.0−mL sample of a solution that is 0.14M in NaCN.
After the solution reaches equilibrium, what concentration of Ag+(aq) remains?,
This reaction practically goes to completion as AgCN is nearly insoluble, using up almost all of the Ag+, so practically no Ag+ remains.
Explanation:The reaction between AgNO3 and NaCN results in the formation of AgCN, which is nearly insoluble. Due to this, the reaction practically goes to completion, consuming almost all the Ag+ ions.
The initial number of moles of Ag+ can be calculated as follows: volume (L) × molarity = 0.130 × 3.0×10−3 = 3.9×10−4 moles.
The initial number of moles of CN- (from NaCN) is: 0.225 × 0.14 = 0.0315 moles.
Since the reaction between Ag+ and CN- is in a 1:1 ratio, all the Ag+ will react until one of the reactants runs out. In this case, it's Ag+ since it's present in a smaller amount. Therefore, practically, no Ag+ remains after the reaction.
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Graphite and iodine are non metals but they shine. Explain it with suitable reasons.
Final answer:
Graphite and iodine are shiny nonmetals due to their structure; graphite's free-moving electrons within layers give it a luster, while iodine's crystalline form reflects light. Both have unique bonding arrangements contributing to their reflective properties.
Explanation:
Graphite and iodine are both nonmetals that exhibit a shiny, lustrous appearance, which is a characteristic more typically associated with metals. The reason behind this lies in their unique structures and bonding arrangements.
Graphite, an allotrope of carbon, has a layered structure with delocalized electrons. These electrons are able to move freely within the layers, which not only gives graphite its electrical conductivity but also contributes to its shine. The carbon atoms within each layer are strongly bonded, but the layers themselves are held together by weaker forces, allowing them to slip past one another and giving graphite its lubricating properties.
Iodine, on the other hand, has a shiny surface due to its crystalline solid form. The structure allows it to reflect light, which gives the appearance of a metallic luster.
A solution is 0.30 m in nh3. what concentration of nh4cl would be required to achieve a buffer solution with a final ph of 9.0? recall the hh equation can be written using ph and pka or poh and pkb. the kb of nh3 is 1.8 x 10–5.
To achieve a buffer solution with a pH of 9.0 using NH₃, the required concentration of NH₄Cl is approximately 0.55 M.
This is determined using the Henderson-Hasselbalch equation.
Key calculations involve finding the pKa and using logarithmic functions.
To determine the concentration of NH₄Cl required to achieve a buffer solution with a pH of 9.0, we use the Henderson-Hasselbalch equation. Given:
The concentration of NH₃ is 0.30 MThe pKb of NH₃ is calculated from the provided Kb (1.8 x 10⁻⁵)pKa of NH⁴⁺ = 14 - pKbFirst, calculate pKb:
pKb = -log(1.8 x 10⁻⁵) ≈ 4.74
Then, calculate pKa:
pKa = 14 - pKb = 14 - 4.74 = 9.26
Using the Henderson-Hasselbalch equation:
pH = pKa + log([NH₃]/[NH₄Cl])
We need a pH of 9.0, so:
9.0 = 9.26 + log(0.30/[NH₄Cl])
Simplifying, we get:
-0.26 = log(0.30/[NH₄Cl])
Taking the antilog, we find:
0.30/[NH₄Cl] = 10^-0.26 ≈ 0.55
Therefore:
[NH₄Cl] = 0.30/0.55 ≈ 0.55 M
To achieve a buffer solution with a pH of 9.0, the concentration of NH₄Cl required is approximately 0.55 M.
The correct question is:
A solution is 0.30 m in NH₃. what concentration of NH₄Cl would be required to achieve a buffer solution with a final ph of 9.0? recall the hh equation can be written using pH and pkₐ or pOH and pkb. The kb of NH₃ is 1.8 x 10⁻⁵.
Any entrée can be labeled "healthy" on a menu as long as it contains natural ingredients. True False
Answer:
False.
Explanation:
Entrée is a culinary term used for a course during a meal service. In parts of the US and Canada, the word entrée is often used to refer to the main dish that is served while in other parts of the world, it usually means the starter or the simple meal that is served before the main dish / course. Entrées can be made of any component but the content of the natural ingredients does not define its healthy status. Thus, it is false to say that any entrée can be labelled "healthy" on a menu as long as it contains natural ingredients.
A particular coal contains 2.5% sulfur by mass. When this coal is burned, the sulfur is converted into sulfur dioxide gas. The sulfur dioxide reacts with solid calcium oxide to form solid calcium sulfite.
Although your question is incomplete I have provide more general answer is provided
The Reaction equation between sulfur dioxide and solid calcium oxide :
[tex]SO_{2}_{(g)} + CaO_{(s)} ---> CaSO_{3}_{(s)}[/tex]
Given that your question is vague I have provided the reaction equation between the Sulphur dioxide and calcium oxide, and the chemical conversion equation of Sulphur to Sulphur dioxide ( gas )
conversion of Sulphur to Sulphur dioxide
= [tex]S_{(s)} + O_{(2)}_{(g)} ----> SO_{2}_{(g)}[/tex]
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Why does the reaction rate of an enzyme-catalyzed reaction plateau at higher reactant (substrate) concentrations?
Final answer:
The plateau in the rate of enzyme-catalyzed reactions at high substrate concentrations occurs because all enzyme active sites become occupied, preventing further increases in reaction rate.
Explanation:
The reaction rate of an enzyme-catalyzed reaction plateaus at higher substrate concentrations because all of the enzyme molecules become saturated with substrate. Initially, as the substrate concentration increases, more active sites on the enzyme molecules are available, leading to an increase in the reaction rate. However, at a certain point, termed the saturation point, all the active sites are occupied, making enzymes unavailable to bind with additional substrate molecules until the current substrate is converted to product and released. This results in a leveling off of the reaction rate, and the reaction cannot proceed any faster regardless of further increases in substrate concentration. This concept is highlighted by the fact that at substrate concentrations higher than 4 X10-5 M, reaction rates do not increase because the enzymes are already working at their maximal rate.
Adding heat to water results in a relatively small temperature change because
A calorie of heat causes a relatively little change in the temperature of water because most of the heat is consumed to break down hydrogen bonds before water molecules can start moving more quickly.
What is heat ?The exchange of "thermal" energy brought on by a temperature differential is known as heat. Think of an isolated system with two subsystems that are initially operating at two distinct temperatures.
Since water has a higher specific heat than other substances, it requires more energy to raise its temperature. This is why using water as a coolant in your car's radiator and in several sectors is beneficial.
The heat required to raise the temperature of liquid water is considerable because hydrogen bonds between the molecules must be broken.
Thus, Heat is absorbed and released as hydrogen bonds form.
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How dose a tree turn chemical energy into thermal energy?
The rays of the sun will go directly to the trees, then trees take up light that absorbs light energy which converting light to chemical potential energy kept in chemical bonds. And when the trees cut into woods and burnt it, it will convert to thermal energy.