Answer:
C,D
Explanation:
Answer:
C D
Explanation:
what kind of solid is crystalline boron
Answer:
It is a network solid, a lattice of many covalent bonds (like diamond, except that it is black rather than transparent).
Explanation:
Answer:
Network Solid
Explanation:
How much heat is added if .7892g of water is increased in temperature by .039 degrees C?
Answer:
=0.1293 J
Explanation:
The heat increase is the change in energy for the water ΔH.
ΔH=MC∅ where M is mass, C is the specific heat capacity for water and ∅ is the change in temperature.
M=0.7892g
C(for water) =4.2 J/g°C
∅=0.039 °C
ΔH=0.7892g×4.2 J/g°C×0.039°C
=0.1293 J
The amount of heat energy added to cause the 0.039°C temperature increase is 0.1293 Joules.
Find the enthalpy of neutralization of HCl and NaOH. 137 cm3 of 2.6 mol dm-3 hydrochloric acid was neutralized by 137 cm3 of 2.6 mol dm-3 NaOH. The temperature rose from 298 K to 325.8 K. The specific heat capacity is the same as water, 4.18 J/K g.
Answer:
Approximately [tex]\rm -89 \; kJ\cdot mol^{-1}[/tex].
Assumption: the density of the solution is equal to the density of pure water.
Explanation:
The enthalpy of neutralization is defined as the enthalpy change for each moles of water produced. (Clark, Physical & Theoretical Chemistry, Chemistry Libretexts.)
Each mole of [tex]\rm NaOH[/tex] formula units will neutralize one mole of [tex]\rm HCl[/tex] to produce one mole of water. [tex]\rm HCl[/tex] and [tex]\rm NaOH[/tex] are available at equal volume and concentration. In other words, there's an equal number of both reactants. All [tex]\rm HCl[/tex] and [tex]\rm NaOH[/tex] will react to form water.
[tex]V(\mathrm{HCl}) = \rm 137\; cm^{3} = 0.137\;dm^{3}[/tex].
[tex]V(\mathrm{NaOH}) = \rm 137\; cm^{3} = 0.137\;dm^{3}[/tex].
[tex]n = c\cdot V = \rm 0.137\;dm^{3} \times 2.6\;mol\cdot dm^{-3} = 0.3652\; mol[/tex].
In other words, there are [tex]\rm 0.3652\; mol[/tex] of [tex]\rm HCl[/tex] and [tex]\rm NaOH[/tex] each. The two will react to produce [tex]\rm 0.3652\; mol[/tex] of water.
How much heat is released?
Assume that the volume of the liquid is equal to the volume of the [tex]\rm HCl[/tex] solution plus the volume of the [tex]\rm NaOH[/tex] solution. That's [tex]\rm 0.274\;dm^{3}[/tex]. Assume that the density of the solution is equal to that of water under room temperature. [tex]\rho(\text{water}) = \rm 1.000\; kg\cdot dm^{-3}[/tex]. The mass of the liquid will be [tex]m = \rho \cdot V = \rm 0.274\; dm^{3} \times 1.000\; kg\cdot dm^{-3} = 0.274\; kg = 274\;g[/tex].
Change in temperature:
[tex]\Delta T = \rm 325.8 - 298 = 27.8\; K[/tex].
Heat that the solution absorbed:
[tex]Q = c\cdot m \cdot \Delta T = \rm 4.18\;J\cdot K^{-1}\cdot g^{-1} \times 274\; g\times 27.8\;K = 36410.216\; J = 36.410216\; kJ[/tex].
That will also be the amount of heat released from the reaction if there's no energy loss.
[tex]\displaystyle \Delta H(\text{Neutralization}) = \frac{-Q}{n(\text{water produced})} = \rm \frac{36.410216\; kJ}{0.3652\; mol} \approx 89\; kJ\cdot mol^{-1}[/tex].
Based on the law of conservation of energy, which state meant is false
The question is incomplete, so it is necessary to write it in its complete form, which you can find in internet.
Question:
Based on the law of conservation of energy, which statement is false?
a. Energy is lost when machines don’t work right.b. We can’t add more energy to the universe.c. We can’t destroy energy that exists in the universe.d. Energy changes from one form to another.Answer:
option a. Energy is lost when machines don't work right.Explanation:
The law of conservation of energy, which is the principle stated by the first law of thermodynamics, states that the energy of the universe is conserved. The energy can be transformed or exchanged between a system and its surrounnding, but the total energy will remain constant.
Then, it is true that we cannot add more energy to the universe (option b.), because, the total energy of the universe remains constant; we can’t destroy energy that exists in the universe (option c.), because, again, as said, the total energy of the universe remains constant; and, also true, energy changes from one form to another, e.g. work to heat, heat to kinetic energy, kinetic energy to potential energy, and so on.
So, options b, c, and d are true.
On the other hand, the statement a. is false: it is not true that energy is lost when machines don't work right; what do happen is that the efficiency of the machine is low and much of the energy, instead of being transformed into useful work, is transformed into heat that is released to the surroundings.
which type of bond is present in hydrogen sulfide
Bonds formed between atoms that have a difference in electronegativity lower than the ionic counterparts are polar covalent bonds. In H2S, the S atom is bonded to 2 H atoms.
Answer:
A. electronegativity < 1.0
Explanation:
Hydrogen --> electronegativity value is 2.1
Sulfur --> electronegativity value is 2.5
∆E, the electronegativity difference is 2.5 - 2.1 = 0.4
So, It is a non polar covalent bond present in [tex]H_2 S[/tex]
Examples :
The electronegative values of H is 2.1
F is 4.0
O is 3.5
N is 3.0
∆E value of HF Hydrogen bond is
4.0 - 2.1 = 1.9
∆E value of H2O Hydrogen bond is
3.5 - 2.1 = 1.4
∆E value of NH3 Hydrogen bond is
3.0 - 2.1 = 0.9
∆E value between 0.5 to 1.7 is a polar covalent bond
∆E value btween 0 to 0.4 is a non polar covalent bond
∆E above 1.7 is an ionic bond
Draw a diagram of water molecules, labeling the hydrogen bond and covalent bond
Answer:
Here you go!
Explanation:
The covalent bonds are the bonds that connect the parts of the water molecule together and the hydrogen bonds connect the individual molecules together.
The diagram of water molecules, labeling the hydrogen bond and covalent bond is attached below.
Each hydrogen atom shares one of its electrons with the oxygen atom, forming a covalent bond. The oxygen atom also has two lone pairs of electrons that are not involved in bonding. This arrangement gives water a bent or V-shaped molecular geometry.
The hydrogen bond is a weak intermolecular force that occurs between the positively charged hydrogen atom of one water molecule and the negatively charged oxygen atom of another water molecule. It is an attraction between the partially positive hydrogen atom and the partially negative oxygen atom. The hydrogen bond is represented by a dotted line between the molecules.
This diagram illustrates the unique properties of water, such as its high boiling point, surface tension, and ability to dissolve many substances. The covalent bonds within the water molecule give it stability, while the hydrogen bonds between water molecules contribute to its cohesive and adhesive properties.
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The electron configuration for chromium is 1s22s22p63s23p63d54s1 instead of 1s22s22p63s23p63d44s1. The configuration is an exception to the _____. Pauli exclusion principle Heisenberg uncertainty principle aufbau principle Schrödinger equation
Answer: The correct answer is Aufbau principle.
Explanation:
Pauli exclusion principle states that no two electrons with in an atom can have all four quantum numbers same.
Heisenberg principle states that it is impossible to measure with high precision the value of momentum and position of an electron.
Aufbau principle states that the electron will occupy the lowest energy level first before occupying the higher energy levels.
Schrodinger equation is used to find the allowed energy levels of quantum mechanical systems of an electron.
Chromium is the 24th element of the periodic table and its electronic configuration must be written as: [tex]1s^22s^22p^63s^23p^63d^44s^2[/tex]
But the actual configuration for this is [tex]1s^22s^22p^63s^23p^63d^54s^1[/tex]
This configuration is an exception to Aufbau's principle because half filled sub-levels is more stable than other configurations.
The actual configuration has half filled 'd' and 's' sub-levels but the expected configuration had fully filled 's' orbital and partially filled 'd' orbital.
Thus, actual configuration is accepted for chromium atom.
Hence, the correct answer is Aufbau's principle.
Answer:
Aufbau principle.
Explanation:
Which soil horizon contains a layer of partially weathered or unweathered rock?
A. E
B. R
C. O
D. C
Answer:
B. R
Explanation:
A layer of partially weathered or unweathered rock is present in R soil horizon
Answer: Option (B)
Explanation: The R-layer represents the unweathered rocks that are located below the surface and is the lowest layer in the soil profile. Here, hard rocks are found which are difficult to break, and are breakable with heavy machineries only. This R-layer makes the foundation of the soil profile that supports the entire overlying series of layers.
Thus, the correct answer is option (B).
Can you explain and read this equation 2Mg + 02 —— 2MgO
Answer:
Here's what I get
Explanation:
There are several ways to read your equation.
2Mg + O₂ ⟶ 2MgO
Magnesium reacts with oxygen to form magnesium oxide Two atoms of magnesium react with one molecule of oxygen to form one formula unit of magnesium oxide. Two moles of magnesium react with one mole of oxygen to form one mole of magnesium oxide.6. What is the pressure of 0.60 moles of a gas if its volume is 10.0 liters at 35.0°C?
Answer: The pressure inside the cylinder will be 1.5 atm. The pressure can be calculated using the Ideal Gas Equation which relates the pressure, volume, temperature, and amount of gas to each other.
Further Explanation
The Ideal Gas Equation is:
[tex]PV = nRT[/tex]
where:
P - pressure (in atm)
V - volume (in L)
n - amount of gas (in moles)
R - universal gas constant [tex]0.08206 \frac{L-atm}{mol-K}[/tex]
T - temperature (in K)
In the problem, we are given the values:
P = ?
V = 10.0 L (3 significant figures)
n = 0.60 moles ( 2 significant figures)
T = 35.0 degrees Celsius (3 significant figures)
We need to convert the temperature to Kelvin before we can use the Ideal Gas Equation. The formula to convert from degree Celsius to Kelvin is:
[tex]Temperature \ in \ Kelvin = Temperature\ in \ Celsius \ + \ 273.15[/tex]
Therefore, for this problem,
[tex]Temperature\ in \ K = 35.0 +273.15\\Temperature\ in \ K = 308.15[/tex]
Solving for P using the Ideal Gas Equation:
[tex]P = \frac{nRT}{V} \\P = \frac{(0.60\ mol) \ (0.08206 \ \frac{L-atm}{mol - K}) \ (308.15\ K) \ }{10.0 \ L} \\P = 1.51\ atm[/tex]
The least number of significant figures is 2, therefore, the final answer must have only 2 significant figures.
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Keywords: Ideal Gas Law, Gas Pressure
A geologist discovered fossils of marine animals in a layer of sedimentary rock in the desert. Based on this discovery, what conclusion can the geologist draw?
Answer:
- the area has been below water in the past
Explanation:
The continents have been moving constantly for the last 2 billion years or so, so the face of the Earth has constantly been changing. What we see in the present as a landscape has been much different in the past, as new landmasses have risen out of the sea, while some have eroded or got molten. This has lead to a situation to have places like deserts, having fossils of marine animals in their sedimentary rocks. This simply tells us that what is now desert, in the past had much lower elevation, and it was covered with sea waters, thus the marine life was thriving. Throughout he geological process, over time, this area got lifted up, so it became part of the landmass, and developed into a desert because of the weather conditions.
Consider the reaction below.
HI + H20 → H30* +1
Which is an acid-conjugate base pair?
HI and H20
H2O and H307
H30+ and I
CHI and I
Answer:
HI and I- represent an acid/conjugate base pair
What is the primary cause for the change in seasons?
A.
the tilt of Earth’s axis
B.
the distance of Earth from the Sun
C.
the position of the Moon between Earth and the Sun
D.
the speed at which Earth rotates
Answer:
A. The tilt of Earth’s axis
Explanation:
The Earth's rotational axis is tilted about 23.5° relative to its orbital plane as it revolves around the Sun.
Thus, the angle of the sun in the sky varies over the year.
For example, if you lived at 45°N, the angle of the Sun in the sky would be 45°, and it would be the beginning of spring (see the diagram below).
The maximum angle of the Sun would be 68.5°.The Sun would be high overhead, and it would be the beginning of summer.
The minimum angle of the Sun would be 21.5°.The Sun would be low in the sky, and it would be the beginning of winter.
B. is wrong. The Earth is closer to the Sun during winter in the northern hemisphere.
C. is wrong. The position of the Moon affects sunlight on Earth only during a solar eclipse.
D is wrong. The speed at which the Earth rotates affects only the length of the day.
The main cause for the change in seasons is the tilt of Earth’s axis. This tilt, combined with Earth's orbit, makes sunlight hit different parts of Earth more directly at various times of the year, leading to temperature changes and thus, seasons.
Explanation:The primary cause for the change in seasons is A. the tilt of Earth’s axis. This axial tilt, combined with Earth's orbit around the Sun, causes sunlight to hit different parts of the Earth more directly during different times of the year. Hence, leading to changes in temperature and ultimately, the change of seasons. It's important to note that it's not the distance of Earth from the Sun (option B), the position of the Moon between Earth and the Sun (option C), or the speed at which Earth rotates (option D) that primarily cause the seasonal changes.
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Enter the net ionic equation for the reaction of AgNO3(aq)
with K2SO4(aq)
. Include phases. Refer to the solubility rules as necessary.
The net ionic equation for the reaction of AgNO3(aq) and K2SO4(aq) can be found by considering the solubility rules. The net ionic equation is 2Ag+(aq) + SO4 2-(aq) → Ag2SO4(s), where Ag2SO4 is the precipitate.
Explanation:The reaction between AgNO3(aq) and K2SO4(aq) involves ionic compounds in aqueous solutions, so we can use the solubility rules to determine the reactants and products. AgNO3(aq) and K2SO4(aq) both dissociate in water to give their individual ions. Next, we can predict the possible products of the reaction, which are Ag2SO4 and KNO3. However, referring to the solubility rules, Ag2SO4(s) is not soluble in water. Hence, a precipitate will form. Therefore, the net ionic equation is:
2Ag+(aq) + SO4 2-(aq) → Ag2SO4(s)
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The net ionic equation is 2Ag⁺(aq) + SO₄²⁻(aq) -> Ag₂SO₄()
Explanation:The net ionic equation for the reaction of AgNO3(aq) with K2SO4(aq) can be determined by first writing the balanced molecular equation, followed by identifying the insoluble substance to write the net ionic equation. Here are the steps:
Write the balanced molecular equation: AgNO3(aq) + K2SO4(aq) -> Ag2SO4(s) + 2KNO3(aq)Identify the insoluble substance using the solubility rules. In this case, Ag2SO4(s) is insoluble.Write the net ionic equation by omitting the spectator ions. The spectator ions are K+(aq) and NO3-(aq). The net ionic equation is: 2Ag+(aq) + SO42-(aq) -> Ag2SO4(s)Therefore, the net ionic equation for the reaction of AgNO3(aq) with K2SO4(aq) is 2Ag+(aq) + SO42-(aq) -> Ag2SO4(s).
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Word equation needed
Answer: 1. Al(0H)3
2. Ca2O
Explanation: During bonding, there will be exchange of ions
1. Al will give OH its 3 valence and OH will give Al its 1 to form Al(0H)3
2. Ca will give O its 1 valence and O will give Ca its 2 to form Ca2O
How would a drastic reduction in plant life on Earth affect the atmosphere?
Levels of oxygen and carbon dioxide would remain approximately the same.
Levels of oxygen would decrease and levels of carbon dioxide would increase.
Levels of oxygen would increase and levels of carbon dioxide would decrease.
Answer:
Levels of oxygen would decrease and levels of carbon dioxide would increase. ( second choice)
Answer: Levels of oxygen would decrease and levels of carbon dioxide would increase.
Explanation:
The rate of photosynthesis will reduce on drastic reduction of the plants. The plants are the carbon sinks they absorb the carbon dioxide from the atmosphere in the absence of plants the carbon dioxide gas will raise in the atmosphere. The oxygen levels in the atmosphere will reduce as photosynthesis will not occur and the oxygen will not be produced as a byproduct of photosynthesis. Also the oxygen is the main requirement for the respiration of living beings except anaerobic bacteria. Thus the oxygen concentration will deplete in the atmosphere.
Which process is an example of a chemical change?
a piece of wood shrinking as it dries out
steam rising from a boiling pot of soup
a metal railing rusting in damp weather
alcohol evaporating from a cotton swab
Answer:
(C) A metal rail rusting Is an example of chemical change.
Explanation:
When a chemical change takes a place a new substance is formed.
HOPE IT HELPS.....
A metal railing rusting in damp weather,is an example of a chemical change.
What is meant by chemical change?A chemical change happens when one chemical substance is transformed into one or more different substances, such as when iron becomes rust. Chemical changes occur through the process of chemical reactions, and the resulting substances have different properties because their atoms and molecules are arranged differently.A metal railing rusting in damp weather,is an example of a chemical change.
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Which of the following statements is NOT true about saturated fats?
A) They contain many carbon-carbon double bonds
B) They are usually solid at room temperature
C) They are usually obtained from animal sources
D) They contain more energy per gram than do unsaturated fats
E) They are not desirable as part of a low cholesterol diet
Answer:
A. They contain many carbon-carbon double bonds.
Explanation:
Saturated fats do not contain double bonds between the carbons. The carbons attached only by single bonds all saturated with hydrogen atoms or in other words, they have many hydrogen atoms clinging to the main skeletal carbon chain, and thus the word saturated.
Saturated fats are the type of fats that are not healthy.
The statement that is NOT true about saturated fats is that they contain many carbon-carbon double bonds.
Explanation:The correct answer is A) They contain many carbon-carbon double bonds. Saturated fats are characterized by having single carbon-carbon bonds in their fatty acid chains, making them saturated with hydrogen atoms. This structure allows them to be solid at room temperature. Saturated fats are commonly found in animal sources, such as meat and dairy products. They also contain more energy per gram compared to unsaturated fats. However, they are not desirable as part of a low-cholesterol diet due to their potential to raise blood cholesterol levels.
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Which of the following statements is true?
A.
Igneous rocks form from the cooling and crystallization of magma.
B.
Fossils are frequently found in metamorphic rock.
C.
Sedimentary rocks are formed as a direct result of chemical weathering.
D.
Extrusive igneous rocks, found in the Earth's lithosphere, are not subject to weathering.
Answer:
Igneous rocks form from the cooling and crystallization of magma.- A.
Final answer:
The true statement is that "igneous rocks form from the cooling and crystallization of magma". Options B, C, and D are incorrect; fossils are not common in metamorphic rocks, sedimentary rocks are also formed from sediments, and extrusive igneous rocks can weather.
Explanation:
The correct statement is A. Igneous rocks form from the cooling and crystallization of magma. Igneous rocks, such as granite and basalt, are formed from the solidification of magma or lava. Metamorphic rocks like schist are formed from pre-existing rocks that undergo transformation due to intense heat and pressure without melting. Contrary to option B, fossils are not frequently found in metamorphic rocks because the conditions that form metamorphic rocks typically destroy organic matter. Sedimentary rocks, mentioned in option C, are indeed a product of weathering, but they're primarily formed from the compaction and cementation of sediments, not chemical weathering alone. Lastly, option D is incorrect because extrusive igneous rocks, like all surface rocks, are subject to weathering processes.
An asteroid hit the Yucatán Peninsula about 65 million years ago,
filling the atmosphere with debris. How could this event have
contributed to the extinction of dinosaurs?
O
A. It sucked up all the carbon.
O
O
O
B. It caused Earth to overheat.
C. It blocked out sunlight.
D. It made it difficult to breathe.
Answer:
C. It blocked out sunlight
Explanation:
The asteroid impact 65 million years ago was devastating for lot of the animals and plants, resulting in a mass extinction, most noticeably of the dinosaurs. The impact itself killed a lot of flora and fauna, but it was the effect afterward that was crucial. From this impact, there was so much debris propelled into the atmosphere that the sunlight got blocked. Once this happened, most of the plants died out as they were not able to perform photosynthesis. Because the plants were dying out, the herbivores were left without food, so soon they followed, and because the herbivores died out, the predators died out to because they were left without food. The winners turned out to be the small and not specialized plants and animals.
Final answer:
The asteroid impact in the Yucatán Peninsula caused debris to C. block sunlight, disrupt photosynthesis, and lead to a steep drop in food availability and global temperatures, contributing significantly to the mass extinction of dinosaurs and altering the course of life on Earth.
Explanation:
The asteroid impact that occurred around 65 million years ago in the Yucatán Peninsula is associated with the extinction of dinosaurs. Following the collision, numerous environmental changes unfolded, which were detrimental to the dinosaurs and other species. One of the primary effects of the asteroid impact was the ejection of a vast amount of debris into the atmosphere. This debris included dust and particles that formed a thick cloud around the Earth, blocking sunlight and significantly reducing the amount of solar radiation reaching the surface of the planet.
With the blockage of sunlight, a catastrophic chain of events was set in motion. Photosynthesis, the process by which plants convert light energy into chemical energy, was severely disrupted. As a result, many plant species perished, leading to a dramatic decline in the food supply for herbivorous dinosaurs. Inevitable consequences ensued for the entire food chain, affecting both plant-eating and meat-eating dinosaurs.
Joel's engine is unable to power his car the way it used to. The spark plug is
working, and the engine is compressing properly, so what could be the
problem?
Answer:
The air to fuel ratio is off
Explanation:
Cars need a certain amount of air mixed in with the fuel, if the amount of either air or fuel is off then it wont be able to be ignited by the spark plug.
The problem with Joel's engine could be premature combustion, caused by using gasoline with a low octane rating. Joel should try using gasoline with a higher octane rating to ensure proper combustion and power delivery in the engine.
Explanation:The problem with Joel's engine could be premature combustion, caused by using gasoline with an octane rating that is too low for the engine. When the fuel ignites prematurely, it can result in uneven burning and cause knocking and pinging in the engine.
Here's an example to help you understand: Imagine you have a small high-performance internal combustion engine with a compression ratio of 10:1. If the gasoline used has a low octane rating, it may ignite prematurely during the engine cycle, leading to poor performance and a decrease in power.
To diagnose and fix the problem, Joel should try using gasoline with a higher octane rating to ensure proper combustion and power delivery in the engine.
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nickel metal is put into lead (iv) acetate solution and produces nickel (ii) acetate and solid lead. if 275 g of lead (iv) acetate reacts with excess nickle. how many moles of nickle (ii) acetate will be produced
Answer:
1.24 mol.
Explanation:
Ni metal reacts with Pb(CH₃COO)₄ according to the balanced equation:2Ni(s) + Pb(CH₃COO)₄ → 2Ni(CH₃COO)₂ + Pb(s),
It is clear that 2 mole of Ni metal reacts with 1 mole of Pb(CH₃COO)₄ to produce 2 mole of Ni(CH₃COO)₂, and 1 mole of Pb.
Firstly, we need to calculate the no. of moles of 275.0 g of Pb(CH₃COO)₄:no. of moles of Pb(CH₃COO)₂ = mass/molar mass = (275.0 g)/(443.38 g/mol) = 0.62 mol.
using cross multiplication:
1.0 mol of Pb(CH₃COO)₄ produces → 2 mol of Ni(CH₃COO)₂, from the stichiometry.
0.62 mol of Pb(CH₃COO)₄ produces → ??? mol of Ni(CH₃COO)₂.
∴ The no. of moles of Ni(CH₃COO)₂ are produced = (0.62 mol)(2.0 mol)/(1.0 mol) = 1.24 mol.
which is true according to the kinetic theory?
A. the particles that make up solids do not move.
B. all particles of matter are in constant motion.
C. all particles of matter move very quickly
D the particles that make up gases are densely packed
Answer: C. all particles of matter move very quickly
Explanation:
Heat is how fast the molecules are moving in something. This means even a solid's molecules are moving.
Answer: C.
Explanation:
What is the volume of 1.25 M hydrochloric acid required to react completely with 45.0 mL of 0.500 M Ba(OH)2?
Answer:
36.0 mL
Explanation:
First, write the balanced reaction.
2HCl + Ba(OH)₂ → BaCl₂ + 2H₂O
Calculate the moles of Ba(OH)₂:
0.500 mol/L × 0.0450 L = 0.0225 mol Ba(OH)₂
Use stoichiometry to find moles of HCl:
0.0225 mol Ba(OH)₂ × (2 mol HCl / mol Ba(OH)₂) = 0.0450 mol HCl
Now calculate the volume needed at the given concentration.
0.0450 mol HCl × (1 L / 1.25 mol) = 0.0360 L HCl
You need 36.0 mL of 1.25 M HCl.
The volume of 1.25M HCl acid required to react completely with 45.0ml of 0.500M [tex]Ba(OH)_{2}[/tex] is 36.0ml.
What are the steps for calculating the volume of HCl?At first, we will write the balanced equation.[tex]2HCl +Ba(OH)_{2}- > BaCl_{2} +2H_{2} O[/tex]
Now, we will calculate the moles of [tex]Ba(OH)_{2}.[/tex].[tex]0.500mol/L*0.0450L=0.0225 mol[/tex]
So, the number of moles in [tex]Ba(OH)_{2}[/tex] is 0.0225 mol.Now, we will use stoichiometry to find the moles of HCl[tex]0.0225mol Ba(OH)_{2}*(2 mol HCl /mol Ba(OH)_{2})=0.0450mol HCl[/tex]
We will now calculate the volume needed at the given concentration[tex]0.0450mol HCl *(1L/1.25mol)=0.0360L HCl[/tex]
[tex]=36.0ml HCl[/tex]
Hence, the volume of 1.25M HCl is 36.0ml.
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Which of the following is not a characteristic of electromagnetic light waves?
they can travel at various speeds through any one material.
Explanation:
This is the best answer for your question
Electromagnetic waves are a form of traverse wave in which the medium travels perpendicular to the direction of the wave. "They can travel at various speeds through any one material" is not a characteristic of Electromagnetic light waves.
Properties of light waves include reflection, refraction, diffraction and interference. They can propagate and travel through a vacuum at the same speed. Electromagnetic light waves propagate and travel at the speed of light.Therefore, they do not travel at various speed through any one material.
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A school board is concerned that student test scores are being affected by
the fact that students do not get enough sleep at night. Which of the
following is a testable hypothesis to use for finding whether or not this is
true?
A. Children need at least two more hours of deep sleep at night than
adults need
B. Children who eat breakfast and lunch achieve higher test scores
than children who skip either meal.
C. Children who get more sleep at night eat healthier meals and
struggle less with obesity.
D. Children who get a minimum of nine hours of sleep per night
achieve higher test scores than children who get fewer than nine
hours of sleep.
Answer: D. Children who get a minimum of nine hours of sleep per night
achieve higher test scores than children who get fewer than nine
hours of sleep.
Children who get a minimum of nine hours of sleep per night achieve higher test scores than children who get fewer than nine hours of sleep. Hence, option D is correct.
What is a testable hypothesis?A hypothesis is testable if there is a possibility of deciding whether it is true or false based on experimentation by anyone.
A direct way that sleep and school performance are connected is through effects on mental function.
Some known problems associated with lack of sleep include Decreased attention.
The ability to concentrate is vital to learning and academic achievement, but insufficient sleep reduces attention and focus.
According to the testable hypothesis, we can say that children who get a minimum of nine hours of sleep per night achieve higher test scores than children who get fewer than nine hours of sleep.
Hence, option D is correct.
Learn more about the testable hypothesis here:
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During the Calvin cycle:
(A) Glucose and water are produced.
(B) Water is split into hydrogen and oxygen.
(C) Light energy is absorbed by chloroplasts.
(D) All of the above.
Answer:
(B) Water is split into hydrogen and oxygen.
Explanation:
During the Calvin cycle, water is split into hydrogen and oxygen.
The Calvin cycle produces only glucose from carbon-di-oxide and thus all the options are false.
Explanation
The Calvin cycle is the second stage of the photosynthesis chemical reaction.
It occurs in the absence of sunlight and after light reaction stage.
So from the light reaction stage oxygen gas is released and in the Calvin cycle the carbon-di-oxide absorbed by the stomata will react with other chemicals leading to formation of glucose.
As the Calvin cycle occurs in the absence of sunlight, the light energy cannot be absorbed by chloroplast during Calvin cycle.
Also the splitting of water into hydrogen and oxygen was completed in light reaction stage and in Calvin cycle only glucose is produced without water molecules.
Thus none of the options given occur during Calvin cycle.
The Calvin cycle only produces glucose from carbon-di-oxide captured by the stomata in the absence of sunlight and water molecules.
Balance the equation KHCO3+ H3PO4 arrow K2HPO4+H20 C02.
Answer:
2KHCO3+ H3PO4 arrow K2HPO4 + 2 H20 + 2C02
Explanation:
2KHCO3+ H3PO4 arrow K2HPO4 + 2 H20 + 2C02
Start with the Ks. Don't start on the right. Just balance the Ks on the left. The reason is that the CO3 is going to break down as well.
2KHCO3+ H3PO4 arrow K2HPO4 + H20 + C02
Leave the PO4 alone. Now look at the Hs that are on the right. There are 5 on the left. Leave the K2HPO4 alone. If you put a 2 in front of tthe H2O then you have a total of 5 Hs on the right.
2KHCO3+ H3PO4 arrow K2HPO4 + 2H20 + C02
There are 2 carbons on the left. You need 2 on the right.
2KHCO3+ H3PO4 arrow K2HPO4 + 2H20 + 2C02
That should do it.
Let's make a table to show balance.
Species K H C PO4- O
Left 2 5 2 1 6 from CO3^(2-)
Right 2 5 2 1 6 from H2O/CO2
1. Which metal is the most reactive? How do you know this?
Answer:
cesium
Explanation:
The most reactive metal on the periodic table is francium. However, francium is a man-made element and only minute quantities have been produced, so for all practical purposes, the most reactive metal is cesium. Cesium reacts explosively with water, though it is predicted francium would react even more vigorously.
A sample of potassium is composed of 23% K-39, 48% K-40 and the remainder K-41. Calculate the average mass
of the sample.
Answer:
[tex]\boxed{\text{40 u}}[/tex]
Explanation:
The atomic mass is the weighted average of the atomic masses of each isotope.
In a weighted average, we multiply each value by a number representing its relative importance.
In this problem, the percent abundance represents the relative importance of each isotope.
Data:
K-39 = 23 %
K-40 = 48 %
Calculations:
(a) Calculate % K-41
K-41 = 100 - 23 - 48 = 29 %
(b) Calculate atomic mass of sample
[tex]\begin{array}{cccc}\\\textbf{Isotope} & \textbf{Mass/u} & \textbf{Abundance} & \textbf{Contribution/u}\\\text{K-39} & 39.0 & 0.23 & 9.0\\\text{K-40} & 40.0 & 0.48 & 19.2\\\text{K-41} & 41.0 & 0.29 & 11.9\\ & \text{TOTAL} & = & 40.0\\\end{array}\\\text{The average atomic mass of the sample is }\boxed{\textbf{40 u}}[/tex]
Final answer:
The average mass of the sample can be calculated by considering the abundance of each isotope of potassium and their respective masses. The average mass of the sample is 100 grams.
Explanation:
The average mass of the sample can be calculated by considering the abundance of each isotope of potassium and their respective masses. Here's how:
Convert the percentages of each isotope to fractions by dividing them by 100.
Multiply each fraction by the atomic mass of the corresponding isotope.
Add up the products to get the average mass.
For example, if we have 100 grams of the sample:
23% of K-39 corresponds to 23 grams of K-39.
48% of K-40 corresponds to 48 grams of K-40.
The remaining 29% of K-41 corresponds to 29 grams of K-41.
Adding up the masses, we get: 23 + 48 + 29 = 100 grams. Therefore, the average mass of the sample is 100 grams.