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.
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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.
Which subatomic particle has the least mass?
electron
proton
neutron
nucleus
the answer is electrons
Final answer:
The subatomic particle with the least mass is the electron, having a mass of about 0.00055 amu, which is significantly lighter than both the proton (1.0073 amu) and the neutron (1.0087 amu).
Explanation:
When comparing subatomic particles such as electrons, protons, and neutrons, the electron is the particle with the least mass. Despite all three being crucial components of an atom, an electron has an extremely small mass compared to protons or neutrons. Specifically, the mass of an electron is about 0.00055 amu (atomic mass units), whereas a proton has a mass of approximately 1.0073 amu, and a neutron has a mass of about 1.0087 amu.
Protons and neutrons, collectively known as nucleons, have masses that are nearly identical. However, the neutron is very slightly more massive. The vast difference in mass between electrons and nucleons (protons and neutrons) means that almost all the atomic mass is concentrated in the atom's nucleus, not in the electrons that orbit it.
how many cups are in 4 liters? 1 L=4.2cups
Answer:
16.8 cups
Explanation:
We are given that there are 4.2 cups in in 1 liter of a liquid and we are to find out the number of cups that there will be in 4 liters.
To find this out, we will use the ratio method.
We know that:
1 L = 4.2 cups
So we can write it as:
[tex]\frac{1L}{4 L} =\frac{4.2 cups}{x}[/tex]
[tex] x = 4 .2 \times 4[/tex]
[tex] x = 1 6 . 8 [/tex]
Therefore, there are 16.8 cups in 4 liters.
What is true of a covalent bond? (03.03)
It is the electrostatic attraction between oppositely charged particle
It is the sharing of electrons by overlapping orbitals
It involves the exchange of electrons from one atom to another
It involves the sharing of neutrons between two nuclei
Answer:
I think B..
Explanation:
It is the sharing of electrons from one atom to another .
Answer:
The answer is b: It is the sharing of electrons by overlapping orbitals
Explanation:
The ionic bong involves the exchange of electrons from one atom to another to keep eight particles in their outermost orbit. In this way the atoms become stable. This happens between a metal, which losing electrons becomes a cation that now has a positive charge, and a non-metal, which accepting electrons becomes an anion that now has a negative charge. So the ionic bond is the electrostatic attraction between oppositely charged particle (cation and anion).
No chemical bond involves sharing neutrons between two nuclei. Chemical bonds occur between the electrons of atoms, which are found in the outer layer around the nuclei.
So, the correct answer is b: It is the sharing of electrons by overlapping orbitals. This happens between two non-metallic elements.
As matter changes, what happens to the energy?
Energy, Temperature, and Changes of State
Matter either loses or absorbs energy when it changes from one state to another. For example, when matter changes from a liquid to a solid, it loses energy. The opposite happens when matter changes from a solid to a liquid.
A hot air balloon contains 5.30 kL of helium gas when the temperature is 12°C. At what temperature will the balloon's volume have increased to 6.00 kL? (Remember to convert to Kelvin and then back to Celcius.)
(A) 50 °C
(B) -21 °C
Answer:
(A) 50 °C
Explanation:
Ideal gas law:
PV = nRT
If pressure is held constant, then:
V₁ / T₁ = V₂ / T₂
Substituting values:
(5.30 kL) / (12 + 273 K) = (6.00 kL) / T
T = 323 K
T = 50 °C
Answer:
Option (A) 50 °C
Explanation:
Thinking process:
Let the volume of the hot air be [tex]V_{1}[/tex] 5.30 k l = 5 300 l = 5.3 m³
The initial temperature will be 12 ° (12 + 273.15) = 285.15 K
The later volume, [tex]V_{2}[/tex] = 6 Kl = 6 000 l = 6 m³
The equation will be:
[tex]\frac{P_{1}V_{1} }{T_{1} } = \frac{P_{2}V_{2} }{T_{2} }[/tex]
If the pressure is the same, then:
[tex]\frac{5.3}{285.15} = \frac{6}{T_{2} }[/tex]
Solving for [tex]T_{2}[/tex] gives:
T₂ = 322.8
= 49.66
= 50°
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
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:
Consider the following unbalanced redox reaction:
NO3- → NO
How many water molecules are needed for balancing?
Answer:
I water molexule
Explanation:
equat8n= 2NO3 + h2O =2 HNO3
Final answer:
Upon balancing the redox reaction NO3- → NO, we find that two water molecules (2 H2O) are required for balancing the reaction, ensuring both mass and charge conservation.
Explanation:
The reaction provided, NO3- → NO, is an unbalanced redox reaction. Balancing redox reactions involves ensuring that both the number of atoms of each element and the charge are balanced on both sides of the equation. Let's focus on the nitrogen and oxygen atoms first, and then balance the hydrogen atoms and the charges. After balancing, the fully balanced equation becomes:
NO3- + 2 H+ + e- → NO + 2 H2O
To confirm the balance, verify that there are equal numbers of nitrogen atoms and oxygen atoms on each side of the equation, as well as that the total charge is balanced. Here we can see that there are the same number of nitrogen atoms (1 on each side) and oxygen atoms (3 on the left, 1 in NO, and 2 in the 2 H2O molecules), which means the number of atoms is balanced. Additionally, the total charge on each side is also the same (-1 on the left side with the nitrate ion and the 2 extra positive charges from the hydrogen ions equaling +1, and 0 on the right side with NO being neutral and water having no charge).
Therefore, two water molecules (2 H2O) are required to balance this redox reaction.
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].
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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What is heat vaporization?
Answer:
D
Explanation:
there is no explanation, I researched the topic
In which layer of the Earth does the motion of the convection currents drive plate movement?
A.)mantle
B.)outer core
C.)asthenosphere
D.)lithosphere
Answer: option (A)
Explanation: The convection current is generates in the mantle due to the heat radiated from the core of the earth. Due to this convection current, the lithospheric plates moves as the upper part of the mantle known as the asthenosphere, is the region which is viscous in nature and drives the plates to move. This is a repeating cycle that constantly forces the plates to move.
Thus the correct answer is option (A).
Answer:
Mantle
Explanation:
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.
How many grams of Fe3O4 are required to react completely with 69.76 grams of H2?
Answer:
=2023.04 grams
Explanation:
Magnetite reacts with hydrogen to produce Iron metal and steam. Steam instead of water is produced as the reaction occurs at temperatures above the boiling point of water.
Fe₃O₄ + 4 H₂ → 3 Fe +4 H₂O
From the equation, 1 mole of Fe₃O₄ reacts with 4 moles of H₂.
69.76 grams of H₂ has the following number of moles.
Number of moles= mass/RAM
=69.76/2
=34.88 moles.
The reaction ratio of Fe₃O₄ to H₂ is 1:4
Thus number of moles of magnetite= (1×34.88)/4
=8.72 moles.
Mass= moles × RAM
=8.72 moles × (56×3+16×4)
=2023.04 grams
3. When atoms combine to form molecules, a (blank) change has occurred.
When atoms combine to form molecules, a chemical change has occurred as there is a chemical reaction involved.
What is a chemical change?
The atoms in the reactants rearrange and link differently throughout a chemical reaction to create one or more new products with properties distinct from the reactants. A chemical change occurs when a new substance is created.Chemical transitions, commonly referred to as chemical reactions, are the conversion of one or more substances into one or more unique, distinct substances.In other words, a chemical reaction involving atom rearrangement is referred to as a chemical transformation.Examples of chemical changes include burning, cooking, rusting, and decaying.Thus, a chemical change takes place when atoms combine to form molecules.
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Which contains elements with similar properties in the periodic table?
The answer is a column.
30 POINTS WILL GIVE BRAINLIEST
_____ numbers are based on the distribution of electrons in a molecule.
Question 4 options:
coefficient
oxidation
electron
chemical
What are repelled in the VSEPR theory?
A. Other molecules
B. Opposite charges
C. Protons in nuclei
D. Electron pairs
Answer:
electron pairs, i just did it on APEX
Explanation:
Final answer:
In VSEPR theory, the elements that are repelled are electron pairs, which include both bonding pairs and lone pairs, dictating the molecular geometry.
Explanation:
The Valence Shell Electron Pair Repulsion (VSEPR) theory predicts the arrangement of electron pairs around each central atom in a molecule. According to this theory, electron pairs are oriented to be as far apart as possible to minimize repulsions. Therefore, the elements that are repelled in VSEPR theory are D. Electron pairs. These include both bonding electron pairs (shared between atoms to make covalent bonds) and lone pairs (non-bonding electron pairs).
In VSEPR theory, the repulsion between electron pairs is a key factor in determining the geometric structure of molecules. For example, in a water molecule (H₂O), the two lone pairs on the oxygen force the hydrogen atoms to adopt a bent arrangement rather than a linear one.
why leather gets hardered after tanning
Answer:
Mutual coagulation takes place
Explanation:
Leather gets hardened after tanning because mutual coagulation takes place.
convert 132,000,000,000,000,000 into number of moles
Answer:
0.15365144685714319697163388678739
Explanation:
1 mole is equal to 6.022^23 somethings (anything) since a mole is a way of representing the amount of somethings. Using avogadro's number rounded to the thousandth's place (you can look up a more specific version) you divide 132... by 6.022^23 to get the amount of moles.
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.
How many molecules of O2 are required to react with 3.00 moles P4?
P4+5O2⟶2P2O5
The reaction requires 15 moles of O2, which equates to 9.03 * 10^24 molecules, to react with 3 moles of P4.
Explanation:To calculate the number of O2 molecules required in this reaction, we refer to the stoichiometric coefficients in the balanced chemical equation. Looking at the equation, we can see that 1 mole of P4 reacts with 5 moles of O2 to produce 2 moles of P2O5. Therefore, 3 moles of P4 would require 3*5=15 moles of O2. To convert moles to molecules, we have to multiply by Avogadro's number (6.022 * 10^23) because there are that many molecules in one mole. Therefore, 15 moles of O2 would equate to 9.03 * 10^24 molecules of O2.
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why do all atoms of an element have the same atomic number, although they may have
different mass numbers?
Answer:
Here’s what I get.
Explanation:
The atomic number is the number of protons in the nucleus of an atom. The number of protons determines the number of electrons. The number of electrons determines the chemical properties of the element,Thus, the atomic number determines the identity of the element.
The atomic mass does not affect the chemical properties, so different isotopes of an element behave alike.
The device shown in the picture is used by electric utility power stations to produce electrical energy from _____ energy
Answer:
mechanical energy
What is a real world example of the colligative property boiling point?
Answer:
Antifreeze
Explanation:
That sounds like a contradiction, doesn't it?
Antifreeze lowers the freezing point of the water in your car's cooling system.
It also raises the boiling point and protects against boil overs.
A 50:50 mixture of ethylene glycol/water boils at 106 °C (223 °F). If the car radiator has a 100 kPa (15 psi) cap, the boiling point increases to 126 °C (258 °F).
Answer:
antifreeze
Explanation:
A 50:50 mixture of ethylene glycol/water boils at 106 °C (223 °F). If the car radiator has a 100 kPa (15 psi) cap, the boiling point increases to 126 °C (258 °F).
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.
Which of the following is an example of chemical energy changing into radiant energy?
A)A fireplaces glowing when lighted
B)A plant using sunlight to make food
C)A child on a swing slowing down as she swings upwards
D)A coil of a toaster glowing when the toaster is switched on
Answer:
D)A coil of a toaster glowing when the toaster is switched on
Explanation:
A coil of a toaster glowing when the toaster is switched on is an example of chemical energy changing into radiant energy.
The toaster is turning into radiant energy because it is getting warmer and cooking.
Answer:
Explanation:
The reaction you are looking for is
hydrocarbon + O2 ====> nCO2 + mH20
in the simplest form.
You have a piece of wood. You burn it. There is going to be a chemical change.
Both heat and light are produced. (radiant energy)
The second best answer is D because you do get radiant energy.
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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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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