Answer: The atomic number of oxygen is "O" .
Explanation:
Because Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds.
What branch of science studies The Periodic Table?
A.Biology
B.Earth Science
Chemistry
Atoms mover slower in the ____________. *
A.heat
B.cold
Atoms move faster in the __________. *
A.heat
B.cold
A nucleus is made of ________ and _________. *
A.protons and electrons
B.electrons and neutrons
C.protons and neutrons
Protons have what type of charge? *
A.neutral
B.negative
C.positive
Neutrons have what type of charge? *
A.neutral
B.negative
C.positive
Atoms have empty space. *
A.True
B.False
What is the center of an atom called? *
A.Neutron
B.Nitrogen
C.Nucleus
The atomic number represents the number of _______. *
A.protons
B.neutrons
C.electrons
What family of elements is most stable? *
A.metals
B.nonmetals
C.Nobel gasses
What scientist is credited with designing The Periodic Table? *
A.Albert Einstein
B.Isaac Newton
C.Dmitri Mendeleev
Atomic mass is found at the _______________.
A.top of the square
B.the middle of the square
C.the bottom of the square
The Periodic Table has elements that are liquids, gasses, and solids. *
A.True
B.False
With an atomic number of 1, which element is the lightest? *
A.Helium
B.Xenon
C.Hydrogen
D.Radon
Answers:
1. Chemistry
2. Cold
3. Heat
4. Protons and neutrons
5. Positive
6. Neutral
7. True
8. Nucleus
9. Protons
10. Nobel gasses
11. Dmitri Mendeleev
12. the bottom of the square
13. True
14. Helium
Determine the vapor pressure of a solution at 25°C that contains 76.6 g of glucose (C6H12O6 ) in 250.0 mL of water. The vapor pressure of pure water at 25°C is 23.8 torr
Answer:
[tex]23.093\ \text{torr}[/tex]
Explanation:
[tex]M_g[/tex] = Molar mass of glucose = 180.2 g/mol
[tex]M_w[/tex] = Molar mass of water = 18 g/mol
[tex]m_g[/tex] = Mass of glucose = 76.6 g
[tex]m_w[/tex] = Mass of water = [tex]250\times 1\ \text{g/mL}=250\text{g}[/tex]
[tex]P_0[/tex] = Vapor pressure of pure water at 25°C = 23.8 torr
The mole fraction of glucose is
[tex]x_g=\dfrac{\dfrac{m_g}{M_g}}{\dfrac{m_g}{M_g}+\dfrac{m_w}{M_w}}=\dfrac{\dfrac{76.6}{180.2}}{\dfrac{76.6}{180.2}+\dfrac{250}{18}}\\\Rightarrow x_g=0.0297[/tex]
Mole fraction of the solute would be
[tex]\dfrac{P_0-P}{P_0}=x_g\\\Rightarrow 0.0297=\dfrac{23.8-P}{23.8}\\\Rightarrow P=23.8-0.0297\times23.8\\\Rightarrow P=23.093\ \text{torr}[/tex]
The vapor pressure of the solution is [tex]23.093\ \text{torr}[/tex].
Calculate the pH during the titration of 20.00 mL of 0.1000 M trimethylamine, (CH3)3N(aq), with 0.2000 M HClO4(aq) after 9.48 mL of the acid have been added.
Complete Question
Calculate the pH during the titration of 20.00 mL of 0.1000 M trimethylamine, (CH3)3N(aq), with 0.2000 M HClO4(aq) after 9.48 mL of the acid have been added.Kb of trimethylamine = 6.5 x 10-5.
Answer:
The pH is [tex]pH = 9.84[/tex]
Explanation:
From the question we are told that
The volume of trimethylamine, (CH3)3N(aq) is [tex]V_{t} = 20.00mL[/tex]
The concentration of trimethylamine is [tex]C_t = 0.1000 \ M[/tex]
The volume of HClO4(aq) is [tex]V_{h} = 9.48 mL[/tex]
The concentration of HClO4(aq) is [tex]C_h = 0.200 M[/tex]
The Kb value is [tex]K_b = 6.5 * 10^{-5}[/tex]
Generally the the pOH of this reaction is mathematically represented as
[tex]pOH = pK_b + log [\frac{N_h}{N_b} ][/tex]
Here [tex]N_h[/tex] is the number of moles of acid which is evaluated as
[tex]N_h = C_h * V_h[/tex]
=> [tex]N_h = 0.200 * 9.48[/tex]
=> [tex]N_h = 1.896[/tex]
Here [tex]N_t[/tex] is the number of moles of acid which is evaluated as
[tex]N_t = C_t * V_t[/tex]
=> [tex]N_t = 0.100 * 20[/tex]
=> [tex]N_t = 2[/tex]
So
[tex]pOH = -log(K_b) + log [\frac{N_h}{N_b} ][/tex]
[tex]pOH = -log(6.5*10^{-5}) + log [\frac{1.896}{2} ][/tex]
=> [tex]pOH = 4.1639[/tex]
Generally the pH is mathematically represented as
[tex]pH = 14 - pOH[/tex]
=> [tex]pH = 14 - 4.1639[/tex]
=> [tex]pH = 9.84[/tex]
4 As a boulder rolls from the top of a hill to the bottom, how do its potential and kinetic energy change? *
A Potential and kinetic energy both increase.
B Potential increases and kinetic decreases.
C Potential decreases and kinetic increases.
D Potential and kinetic energy both decrease..
Answer:
c. Potential decreases and kinetic increases.
Explanation:
As the boulder is rolling down the hill, potential energy decreases as kinetic energy increases.
Please Brainliest me
What does Gravity means
Please it’s due today need help please
A gram sample of a KCl and KClO3 mixture was found to contain 0.00875 mol of KClO3. What is the percent by mass of KClO3 in the original mixture?
Answer:
53.5%
Explanation:
Step 1: Given data
Mass of the sample: we will suppose it is 2.00 g to show the procedureMoles of KClO₃: 0.00875 molStep 2: Calculate the mass corresponding to 0.00875 moles of KClO₃
The molar mass of KClO₃ is 122.55 g/mol.
0.00875 mol × 122.55 g/mol. = 1.07 g
Step 3: Calculate the percent by mass of KClO₃ in the mixture
We will use the following expression.
%m/m = mass of KClO₃/mass of the sample × 100%
%m/m = 1.07 g/2.00 g × 100%
%m/m = 53.5%
The percent by mass of KClO3 in the original mixture is 53.5%.
Calculation of the percentage:Since
The mass of the sample should be 2.00 g
Moles of KClO₃: 0.00875 mol
The molar mass of KClO₃ is 122.55 g/mol.
Now the mass is
= 0.00875 mol × 122.55 g/mol.
= 1.07 g
Now the percentage should be
= mass of KClO₃/mass of the sample × 100%
= 1.07 g/2.00 g × 100%
= 53.5%
hence, The percent by mass of KClO3 in the original mixture is 53.5%.
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Please help me please i will mark you brainliest. In the nucleus of an atom, there are 17 protons and 18 neutrons. What is the atomic number? What is the atomic mass? How many electrons are there? Be sure to answer all 3 questions.
Answer:
i can only help with 2 :( atimic mass is: 35.453 and number of electrons is:17
Explanation:
Please it's due today
Answer:
B
Explanation:
Newton's third law. states that:
Action and reaction are equal and opposite.
3 Which of the following best represents potential energy? *
A Air leaking rapidly from a car tire.
B A marble sitting at the top of a ramp.
C Heat radiating from a large forest fire.
D Water flowing through a rubber hose.
Answer:
Its B
Explanation:
The first excited electronic energy level of the helium atom is 3.13 x 10-18 J above the ground level. Estimate the temperature at which the electronic motion will begin to make a significant contribution to the heat capacity. That is, at what temperature will the ratio of the population of the first excited state to the ground state be 5.0%?
Answer:
75603.86473 K
Explanation:
Given that:
The 1st excited electronic energy level of He atom = 3.13 × 10⁻¹⁸ J
The objective of this question is to estimate the temperature at which the ratio of the population will be 5.0 between the first excited state to the ground state.
The formula for estimating the ratio of population in 1st excited state to the ground state can be computed as:
[tex]\dfrac{N_2}{N_1} = e ^{^{-\dfrac{(E_2-E_1)}{KT}}} = e ^{^{-\dfrac{(\Delta E)}{KT}}}[/tex]
From the above equation:
Δ E = energy difference = 3.13 × 10⁻¹⁸ J
k = Boltzmann constant = 1.38 × 10⁻²³ J/K
[tex]\dfrac{N_2}{N_1} = 0.5[/tex]
Thus:
[tex]0.05 =e^{^{ -\dfrac{3.13 \times 10^{-18} \ J}{1.38\times 10^{-23 \ J/K}\times T}}}[/tex]
[tex]In (0.05) = { -\dfrac{3.13 \times 10^{-18} \ J}{1.38\times 10^{-23 \ J/K}\times T}}}[/tex]
[tex]-3.00 = { -\dfrac{3.13 \times 10^{-18} \ J}{1.38\times 10^{-23 \ J/K}\times T}}}[/tex]
[tex]-3.00 = -226811.5942 \times \dfrac{1}{T}[/tex]
[tex]T = \dfrac{-226811.5942}{-3.00 }[/tex]
T = 75603.86473 K
Which element is most likely suspected?
iron
Sulfur
Chromium
Nickel
Answer: sulfur
Explanation:
Answer:
its sulfur babes
Explanation:
Sulfite is similar to hydroxide in its behavior as a ligand: most sulfites are insoluble in water, but excess sulfite can result in the formation of a complex ion. Write the two equilibrium reactions of sulfite with the copper(II) ion that show this behavior.
Answer:
[tex]$Cu_2+(SO_3)^2 \rightleftharpoons CuSO_3 \ (insoluble)$[/tex]
[tex]$Cu_2+2(SO_3)^2 \rightleftharpoons [Cu(SO_3)_2]_2 \ (soluble)$[/tex]
Explanation:
A ligand may be defined as a molecule or an ion or that binds to the central metal atom in order to form a more coordination complex. Sulfite is one such ligand and it behaves similarly as hydroxide as a ligand.
Now, according to the question, when we react copper with sulfite ion, it forms copper sulfite. The equation is
[tex]$Cu_2+(SO_3)^2 \rightleftharpoons CuSO_3 \ (insoluble)$[/tex]
Now when excess of the sulfite ion is used in the reaction, we get a complex formation, which is shown by
[tex]$Cu_2+2(SO_3)^2 \rightleftharpoons [Cu(SO_3)_2]_2 \ (soluble)$[/tex]
The way the sulfite reacts is quite similar to hydroxide ion where they form a complex ion when hydroxide ion in excess is used in the reaction with metal cation.
PLZ HELP ASAP
Which would increase the reaction rate?
Check all that apply.
A. Stirring the reaction
B. Raising the activation energy
O C. Adding a catalyst
D. Raising the temperature
Answer:
adding a catalyst will increase the reaction rate.
Explanation:
im like 95% sure thats right.
Answer:
A. C. D
Explanation:
ap ex
What shape is the s sublevel? *
sphere
freaky
peanut
daisy
Answer:
Sphere
Explanation:
The shape of the s-sublevel is spherical in shape.
This sublevel has an azimuthal quantum number of 0 and it is spherical in shape;
p - sublevel has a dumb-bell shape d - sublevel has double dumb - bell shape f - sublevel has a complex shapeA) Earlier you were told that of all of the 14 solutes you will be studying, the only one that is not appreciably ionized in water is aqueous ammonia. What does this statement imply about the equilibrium point of the reaction involving aqueous ammonia/ammonium hydroxide?B) Use your results and conclusions from part (a) to explain why a complicated name like Aqueous ammonia/ammonium hydroxide is used for this solution?
Answer:
Throughout the overview section following portion, the description and according to particular circumstance is defined.
Explanation:
As per the question,
⇒ [tex]NH_3(aq)+H_2O\leftrightarrow NH_4+(aq)+OH-(aq)[/tex]
A weak basis seems to be NH3. It serves as a base since the aqueous solution or phase is protonated. But NH3 +, just becoming a weak base, is therefore deprotonated into form NH3, and therefore also 90% of ammonia becomes found throughout NH3 state in aqueous solution.⇒ [tex]NH_3+(aq) \leftrightarrow NH_3(aq)+H+(aq)[/tex]
However, it is also available in NH3 form throughout the aqueous solution much of the moment.
Using the equations
2 Fe (s) + 3 Cl₂ (g) → 2 FeCl₃ (s) ∆H° = -800.0 kJ/mol
Si(s) + 2 Cl₂ (g) → SiCl₄ (s) ∆H° = -640.1 kJ/mol
Determine the enthalpy (in kJ/mol) for the reaction
3 SiCl₄ (s) + 4 Fe (s) → 4 FeCl₃ (s) + 3 Si (s)
The enthalpy : 320.3 kJ/mol
Further explanationThe change in enthalpy in the formation of 1 mole of the elements is called enthalpy of formation
The enthalpy of formation measured in standard conditions (25 ° C, 1 atm) is called the standard enthalpy of formation (ΔHf °)
Based on the principle of Hess's Law,
the change in enthalpy of a reaction will be the same even though it is through several stages or ways
Reaction
2Fe (s) + 3Cl₂ (g) → 2FeCl₃ (s) ∆H° = -800.0 kJ/mol x 2
4Fe (s) + 6Cl₂ (g) → 4FeCl₃ (s) ∆H° = -1600.0 kJ/mol
Si(s) + 2 Cl₂ (g) → SiCl₄ (s) ∆H° = -640.1 kJ/mol
Reverse
SiCl₄ (s) → Si(s) + 2 Cl₂ (g) ∆H° = 640.1 kJ/mol x 3
3SiCl₄ (s) → 3Si(s) + 6Cl₂ (g) ∆H° = 1920.3 kJ/mol
------------------------------------------------------------------------ +
3 SiCl₄ (s) + 4 Fe (s) → 4 FeCl₃ (s) + 3 Si (s) ∆H° = 320.3 kJ/mol
The enthalpy for the formation of 4 moles of [tex]\rm FeCl_3[/tex] has been 320.3 kJ/mol.
The enthalpy of formation of 1 mole at standard temperature and pressure has been termed the standard enthalpy of formation.
The reaction enthalpy to be calculated has reactants of 3 moles of [tex]\rm SiCl_4[/tex], and 4 moles of Fe.
The enthalpy for the formation of [tex]\rm SiCl_4[/tex] has been -640.1 kJ/mol.
The enthalpy for the dissociation of [tex]\rm SiCl_4[/tex] has been the reverse of the formation reaction = +640.1 kJ/mol.
The enthalpy for the dissociation of 3 moles of [tex]\rm SiCl_4[/tex] has been = 3 [tex]\times[/tex] 640.1 kJ/mol.
The enthalpy for the dissociation of 3 moles of [tex]\rm SiCl_4[/tex] has been = 1920.3 kJ/mol.
The enthalpy for the formation of 2 moles of [tex]\rm FeCl_3[/tex] = -800 kJ/mol
The enthalpy for the formation of 4 moles of [tex]\rm FeCl_3[/tex] = -1600 kJ/mol.
The final reaction has 3 moles of [tex]\rm SiCl_4[/tex], and 4 moles of [tex]\rm FeCl_3[/tex].
Thus, the final enthalpy of reaction will be: 1920 kJ/mol + (-1600 kJ/mol)
The final enthalpy of reaction will be = 320.3 kJ/mol.
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2. Find the ΔH for the reaction below, given the following reactions and subsequent ΔH
values:
2C2(g) + H2O(g) → C2H2(g) + ⁵/₂ O2(g)
C2H2(g) + 2H2(g) → C2H6(g) ΔH = –94.5 kJ
H2O(g) → H2(g) + ½ O2 (g) ΔH =71.2 kJ
C2H6(g) + ⁷/₂ O2(g) → 2 CO2(g) + 3 H2O(g) ΔH = –283 kJ
If 0.0806 mol CaCl2 is dissolved in water to make a 0.490 M solution, what is the volume of the solution?
Answer:
0.16 L
Explanation:
From the question given above, the following data were obtained:
Mole = 0.0806 mole
Molarity = 0.490 M
Volume =?
Molarity is simply defined as the mole of solute per unit litre of the solution. Mathematically, it is expressed as:
Molarity = mole /Volume
With the above formula, we can obtain the volume of the solution as illustrated below:
Mole = 0.0806 mole
Molarity = 0.490 M
Volume =?
Molarity = mole /Volume
0.490 = 0.0806/volume
Cross multiply
0.490 × volume = 0.0806
Divide both side by 0.490
Volume = 0.0806 / 0.490
Volume of solution = 0.16 L
Thus, the volume of the solution is 0.16 L.
A solution is a mixture of solute in the solvent. The volume of the solution is 0.16 L.
What is a solution?A solution is a mixture of solute in the solvent.
An example of a solution is a mixture of salt in water.
Given,
Moles = 0.0806 mol [tex]\rm CaCl_2[/tex]
Molarity = 0.490 M
To find: the volume of the solution
[tex]Molarity = \dfrac{n}{V}[/tex]
Putting the values
[tex]0.490 M = \dfrac{ 0.0806}{V}\\\\0.490 M \times V = 0.0806\\\\Divide\; both\;side\; with\; 0.490\\\\V= \dfrac{ 0.0806}{0.490}=0.16 L[/tex]
Thus, the volume so the solution is 0.16 l.
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How is active immunity different from passive immunity? Give examples of both active and passive natural and artificial immunity.
Hugh wrote the properties of physical and chemical weathering in the table shown.
Types of Weathering
Physical Weathering
Chemical Weathering
Temperature may break the rocks Can be caused by chemicals in water
Can be caused by snow and pressure Composition of rock remains same
Why is Hugh's table incorrect? (5 points)
a
Chemicals in water cause physical weathering.
b
ос
Temperature is unable to break rocks physically.
Chemical weathering changes the composition of rocks.
Physical weathering is unaffected by snow and pressure.
Od
Answer:
I am sure that the C one is correct
Answer:
how is this college level..im doing this in middle school..
Explanation:
The indicator phenolphthalein is added to the _____________.
a. Analyte
b. Water
c. Solute
d. Titrant
Answer:
A
Explanation:
I took the test
What factors affect the speed of a wave? Check all that apply. the amplitude of the wave the energy of the wave the temperature of the medium the type of wave the type of medium
Answer:
I believe its 1,2, and 5
Explanation:
C D E
temperature of medium
type of wave
type of medium
A Beer's Law Plot of sample A gives a slope equal to 1.2 M-1cm-1. Calculate molar concentration of this sample at a wavelength of 420 nm and an absorbance reading of 0.23 in a 1 cm cuvette.
Answer:
[tex]0.192\ \text{M}[/tex]
Explanation:
A = Absorbance of solution
E = Molar absorptivity
l = Length of cuvette = 1 cm
c = Concentration of solution
Beer's law is given by
[tex]A=Elc[/tex]
The equation of a straight line is given by
[tex]y=mx+c[/tex]
Comparing the above equations we get
Value on [tex]y[/tex] axis = A = Absorbance of solution = 0.23
[tex]m[/tex] = Slope of line = El = Molar absorptivity multiplied with length = [tex]1.2\times 1\ \text{M}^{-1}[/tex]
[tex]x[/tex] = Value of x axis = c = Concentration of solution
So we get
[tex]c=\dfrac{A}{El}\\\Rightarrow c=\dfrac{0.23}{1.2\times 1}\\\Rightarrow c=0.192\ \text{M}[/tex]
The molar concentration of the sample is [tex]0.192\ \text{M}[/tex]
What is the name of the region (on the graph) where the temperature remains constant while heat is being absorbed (or released)?
Answer:
A heating curve graphically represents the phase transitions that a substance undergoes as heat is added to it. The plateaus on the curve mark the phase changes. The temperature remains constant during these phase transitions.
C is the element symbol for which element?
a. Carbon
b. Cadmium
c. Celenium
d. Chlorine
Answer:
Carbon
Explanation:
what processes add methane (CH4) to the atmosphere
Answer:
Cultivated rice paddies
Drilling of natural deposits
Fossil fuel use
Burning of biomass
Landfills
Explanation:
The bulk of the methane released into the atmosphere are as a result of various human activities.
Cultivated rice paddies are a known source of methaneThe drilling of natural deposits and their exploration can release some methane into the atmosphereBurning of fossil fuel and biomass is a source of methane Landfills produces methane as organic materials begins to decay.How is filtration done?
What is the difference between residue and filtrate?
Answer:
residue is whatever remains after something else has been removed while filtrate is the liquid or solution that has passed through a filter, and which has been separated from the filtride.
filtration id done by placing a filter paper on the beaker or container then pour the filtride then let it settle and it will pass through and you will have the fitrate and residue
Explanation:
The freezing point of a solution the freezing point of the pure solvent
Answer:
This means that a solution must be cooled to a lower temperature than the pure solvent in order for freezing to occur.
Explanation:
Answer:
Freezing Point Depression. The freezing point of a solution is less than the freezing point of the pure solvent. This means that a solution must be cooled to a lower temperature than the pure solvent in order for freezing to occur
what is the equation for the esterification of glycerol and three palmitic acid
Answer:
Pentyl Ethanoate, CH3COOC5H11, which smells like bananas, is produced from the esterification reaction: CH3COOH(aq) +C5H11OH(aq) → CH3COOC5H11(aq) + H … 2O(l) A reaction uses 3.58g of CH3COOH and 4.75g of C5H11OH and has a yield of 45.00%. Determine the mass of ester that foorms
A student writes Ba?- as the symbol for a barium ion. Explain what is incorrect about the symbol.
Answer:
ion is missing
Explanation: