Answer:
line segment of length 8 between the vertices at (-1, -2) and (-1, 6)Explanation:
The equation can be rearranged to standard form.
(y^2 -4y) -4(x^2 +2x) = 16
(y^2 -4y +4) -4(x^2 +2x +1) = 16 +4 -4
(y -2)^2 -4(x +1)^2 = 16
(y -2)^2 /16 -(x +1)^2/4 = 1
This is of the form ...
(y -k)^2/a^2 -(x -h)^2/b^2 = 1
where the transverse axis is 2a and the center is (h, k). Here, a=4, so 2a = 8.
The transverse axis is a vertical line segment of length 8, centered on (-1, 2).
Consider the proportionality below.
PV ont
What does this best represent?
Dalton's law
Charles's law
ideal gas law
combined gas law
Answer:
Ideal gas law
Explanation:
The expression is the ideal gas law when properly written;
PV = nRT
where P is the pressure of the gas
V is the volume of the gas
n is the number of moles of the gas
R is the gas constant
T is the temperature
The ideal gas law is derieved from the three major gas laws;
--- Boyle's law, Charles's law and Avogadro's law
what name did wegener give to the single large landmass composed of all continents
Answer:
The large landmass was named Pangea
Answer:
The names of all continents is Pangaea given by Alfred Wegener in 1912
Explanation:
The name Pangaea or Pangea is derived from the Greek pan that in english means Whole and Gaia that in english means Land. The idea was not new because before Wegener, other scientist have proposed the idea of a huge landmass and then the separation by continents. but Wegener was the first to use the term continental drift.
The continental drift means that the continents are moving form each other since millions of years due to the mantle convection. This theory has been replaced by tectonic plate theory.
why does matter change from one phase to another
Answer:
the state of matter depends on its temperature and pressure. example, at constant pressure of 1atm (atmospheric pressure), water at 100 degrees Celsius is vapor, and at different phases at different temperature. Note that's at pressure other than 1atm, water will not boil (be vaporized) at 100 degrees Celsius, it could be lesser or higher(depending on whether pressure is increased or decreased).
Therefore, the state of mater changes with respect to temperature and pressure action on it.
A person suspects that an unknown liquid is water. he adds 110.0 J of heat to 55.0 g of liquid. The temperature of the liquid increases by 2.1 Celsius. I s the liquid water?The specific heat of water is 4.18 J/ g-Celsius.Please explain answer
Explanation:
First thing first, you mistyped the specific heat of water, which should be
c
water
=
4.18
J
g
∘
C
Now, a substance's specific heat tells you how much heat is required to increase the temperature of
1 g
of that substance by
1
∘
C
.
In the case of water, you would need
4.18 J
to increase the temperature of
1 g
of water by
1
∘
C
.
Notice that your sample of water has a mass of
1 g
as well, which means that the only factor that will determine the amount of heat needed will be the difference in temperature.
The equation that establishes a relationshop between heat and change in temperature looks like this
q
=
m
⋅
c
⋅
Δ
T
, where
q
- heat absorbed
c
- the specific heat of the substance, in your case of water
Δ
T
- the change in temperature, defined as the difference between the final temperature and the initial temperature
Plug in your values and solve for
q
to get
q
=
1.00
g
⋅
4.18
J
g
⋅
∘
C
⋅
(
83.7
−
26.5
)
∘
C
q
=
239.096 J
Rounded to three sig figs, the answer will be
q
=
239 J
Which statement is the best description of a chemical bond?
A. A chemical bond connects 2 different molecules.
B. A chemical bond holds atoms together.
c. A chemical bond turns molecules into atoms.
D. A chemical bond identifies atoms in a molecule.
Answer:
B. is the correct answer
A chemical bond holds atoms together,is the statement that description of a chemical bond.
What is meant by chemical bond?A chemical bond is what holds atoms together in molecules. Bonds arise from the electrostatic forces between positively charged atomic nuclei and negatively charged electrons (the positions of which in space are determined by quantum mechanics).A chemical bond holds atoms together,is the statement that description of a chemical bond.
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Consider the chemical reaction below.
Zn(s)+ 2H*(aq) → Zn2+ (aq) + H2(g)
Which half reaction correctly represents reduction for this equation?
Zn(s) → Zn2+ (aq)+2e
2H* (aq)+2e → H2(g)
Zn(s) → Zn?- (aq)+e"
2H* (aq)+e™ → H2(g)
Answer: [tex]2H^++2e^-\rightarrow H_2(g)[/tex]
Explanation:
Oxidation-reduction reaction or redox reaction is defined as the reaction in which oxidation and reduction reactions occur simultaneously.
Oxidation reaction is defined as the reaction in which a substance looses its electrons. The oxidation state of the substance increases.
Reduction reaction is defined as the reaction in which a substance gains electrons. The oxidation state of the substance gets reduced.
For the given reactio:
[tex]Zn(s)+2H^+\rightarrow Zn^{2+}+H_2[/tex]
On reactant side:
Oxidation state of zinc= 0
Oxidation state of hydrogen = +21
On product side:
Oxidation state of zinc = +2
Oxidation state of hydrogen = 0
The oxidation state of hydrogen reduces from +1 to 0, it is getting reduced. Thus, it is getting reduced and it undergoes reduction reaction
Hence, the correct answer is [tex]2H^++2e^-\rightarrow H_2(g)[/tex]
Answer:
2H+(aq) + 2e– → H2(g) or B.)
on edge 2023
What is the pH of a solution of 0.400 M CH₃NH₂ containing 0.250 M CH₃NH₃I? (Kb of CH₃NH₂ is 4.4 × 10⁻⁴)
Answer:
[tex]\boxed{\text{10.84}}[/tex]
Explanation:
A solution of a weak base and its conjugate acid is a buffer.
The equation for the equilibrium is
[tex]\rm CH$_3$NH$_2$ + H$_2$O $\, \rightleftharpoons \,$ CH$_3$NH$_2$+ H$_{3}$O$^{+}$\\\text{For ease of typing, let's rewrite this equation as}\\\rm B + H$_2$O $\longrightarrow \,$ BH$^{+}$ + OH$^{-}$; $K_{\text{b}}$ = 4.4 \times 10^{-4}$[/tex]
The Henderson-Hasselbalch equation for a basic buffer is
[tex]\text{pOH} = \text{p}K_{\text{b}} + \log\dfrac{[\text{BH}^{+}]}{\text{[B]}}[/tex]
Data:
[B] = 0.400 mol·L⁻¹
[BH⁺] = 0.250 mol·L⁻¹
Kb = 4.4 × 10⁻⁴
Calculations:
(a) Calculate pKb
pKb = -log(4.4× 10⁻⁴) = 3.36
(b) Calculate the pH
[tex]\text{pOH} = 3.36 + \log \dfrac{0.250}{0.400} = 3.36 + \log 0.625 = 3.36 - 0.204 = 3.16\\\\\text{pH} =14.00 -3.16 = \mathbf{10.84}\\\\\text{The pH of the solution is }\boxed{\textbf{10.84}}[/tex]
The pH of a solution of 0.400 M CH₃NH₂ containing 0.250 M CH₃NH₃I = 10.84
This given solution contains a weak base (CH₃NH₂) and the conjugate acid of that weak base (CH₃NH₃I) which makes a Buffer.
To find the pH of a basic buffer, we can use a modification of the Henderson Hasselbalch equation.We know that
[tex]pOH=pK_b+log\frac{[salt]}{[base]}[/tex]
or, [tex]pH=pK_a+log\frac{[base]}{[salt]}[/tex]
CH₃NH₂ is the base and CH₃NH₃I is the corresponding conjugate acid (salt).
Given:
[base] = 0.400 M
[salt] or [acid] = 0.250 M
= 4.4 * 10-4
So = 3.36
solution:
Putting in the equation,
[tex]pOH= 3.36 +log\frac{0.250\ M}{0.400\ M}[/tex]
pOH= 3.16
So pH = 14 - pOH
= 10.84
Thus, the pH of a solution of 0.400 M CH₃NH₂ containing 0.250 M CH₃NH₃I = 10.84
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Which element has an atomic number of 16?
Answer:
Sulfur
Explanation:
the atomic number is the number of protons in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table
Sulfur has 16 protons in its nucleus
The element with an atomic number of 16 is sulfur.
How do we explain?Sulfur is a chemical element that has an atomic number of 16. It is represented by the symbol "S" on the periodic table.
Sulfur is a nonmetal and belongs to Group 16, also known as the chalcogens, on the periodic table. It is located in the third period. It is classified as a multivalent element, meaning it can form compounds with various oxidation states.
In its pure form, sulfur is a yellow, brittle solid. It is known for its distinctive odor, often described as being similar to rotten eggs. Sulfur is found in various minerals and is also a component of many natural resources such as coal, petroleum, and natural gas.
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how much does 12 liters of ammonia weighs at room temperature and pressure (293K and 100 kPa)?
Answer:
8.38g
Explanation:
Given parameters:
Volume of the gas = 12L or 12dm³
Temperature = 293k
Pressure = 100kPa
Unknown: mass of the ammonia gas = ?
_____ Now let us take the unit of pressure to atm:
Pressure = 100 kPa
1kPa = 0.00986923atm
100kPa = 100 x 0.00986923 = 0.987atm
Solution:
From the ideal gas law, we can find the number of moles of the ammonia gas. Using the number of moles, it would be possible to find the mass of the ammonia.
PV = nRT
n = [tex]\frac{PV}{RT}[/tex]
Where R is the gas constant and its value is 0.082atmdm³mol⁻¹K⁻¹
n = [tex]\frac{0.987atm x 12dm³}{0.082atmdm³mol⁻¹K⁻¹ x 293K}[/tex]
n = 0.493mol
We know that, mass = number of moles x molar mass
Molar mass of NH₃ = 14 + (3x1) = 17gmol⁻¹
mass of NH₃ = 0.493 x 17 = 8.38g
Which cohesive forces are the strongest in water?
A.) London dispersion forces
B.) dipole interactions
C.) hydrogen bonding interactions.
D.) All intermolecular forces in water are equally strong.
Which describes the fourth state of matter known as plasma?
A It is a liquid containing nuclei and electrons.
B It is a gas containing nuclei and electrons.
C It is a liquid containing electrons created by fusion.
D It is a gas containing nuclei created by fusion.
Answer:
the answer is letter B. it is a gas containing nuclei and electrons.
B. It is a gas containing nuclei and electrons.
What is the fourth state of matter?Plasma is called the fourth state of matter. It is a state of matter in which an ionized substance turns into distinctly electrically conductive to the point that long-range electric and magnetic fields dominate its behavior.
A plasma is an ionized gas.a gas into which sufficient energy is provided to free electrons from atoms or molecules to allow both species, ions, and electrons, to coexist. Plasma is the fourth state of matter.Learn more about Plasma here
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Which is a fossil fuel?
A.nuclear
B.Biomass
C.geothermal
D.coal
Answer:
Coal
Explanation:
Coal is composed of the remains of dead animals and plants, being pressed down over the course of thousands of years.
(Also can I please have Brainliest? I need it to level up)
Answer:
coal
Explanation:
a fossil fuel is a general term for buried combustible geologic deposits of organic materials formed from decayed plants and animals. hope this helps i took physical science.
How many grams of CaCl2
are needed to make 344.9
g of a solution that is 32.0
% (m/m) CaCl2
in water? Note that mass is not technically the same thing as weight, but % (m/m) has the same meaning as % (w/w).
grams CaCl2=
g
How many grams of water are needed to make this solution?
grams H2O=
Answer:
[tex]\boxed{\text{110.4 g of CaCl$_{2 }$ and 234.5 g of water}}[/tex]
Explanation:
1. Mass of CaCl₂
[tex]\text{Let m = mass of CaCl}_{2}\\\\\begin{array}{rcl}\text{Mass percent} & = & \dfrac{\text{Mass of CaCl}_{2}}{\text{Total mass}} \times 100 \%\\\\32.0 \% & = & \dfrac{m}{\text{344.9 g}} \times 100 \% \\\\\text{32.0 $\times$ 344.9 g} & = & 100 m\\\\m & = &\dfrac{\text{32.0 $\times$ 344.9 g}}{100}\\\\ & = &\textbf{110.4 g}\\\end{array}\\\text{You need $\boxed{\textbf{110.4 g}}$ of calcium chloride}[/tex]
2. Mass of water
[tex]\text{Let m = mass of water}\\\begin{array}{rcl}\\\text{Mass of water + mass of CaCl}_{2} & = & \text{Mass of solution}\\m + 110.4 & = & 344.9\\m & = &\mathbf{234.5}\\\end{array}\\\text{The mass of water needed is $\boxed{\textbf{234.5 g}}$}[/tex]
which of the following compounds is not likely to have ionic bonds LiF, NaCI, CH4, MgF2
Methane CH[tex]_{4}[/tex] does not have ionic bonds. Because of the close value of electronegativity of the carbon and hydrogen atoms the electrons are shared forming covalent bonds.
Answer:
[tex]CH_4[/tex] is not likely to have ionic bonds
Explanation:
Ionic bond is formed between a metal and a non metal.
[tex]NaCl, LiF[/tex] and [tex]MgF_2[/tex] are examples in which we see metal bonded with a non-metal.
Na, Li, Mg are all metals and Cl, F are non metals.
[tex]CH_4[/tex] contains only non metals. Covalent bond is the bond present among non metallic compounds.
We can identify a bond as an ionic bond or a covalent bond based on the electronegativity values of the atoms present in it.
For example [tex]H_2 S[/tex]
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
how many liters of radon gas would be in 3.43 moles at standard temperature and pressure (273K and 100 kPa)?
Final answer:
Approximately 9.32 liters of radon gas would be in 3.43 moles at standard temperature and pressure (273K and 100 kPa).
Explanation:
To find the number of liters of radon gas in 3.43 moles at standard temperature and pressure (STP), we can use the ideal gas law equation: PV = nRT.
Substituting the given values into the equation:
Pressure (P) = 100 kPa
Temperature (T) = 273 K
Number of moles (n) = 3.43 mol
Ideal gas constant (R) = 8.31 L·kPa/mol·K
Volume (V) is what we need to find.
Using the equation PV = nRT, we can rearrange it to solve for the volume:
V = (nRT) / P
Plugging in the values:
V = (3.43 mol)(8.31 L·kPa/mol·K)(273 K) / 100 kPa
V ≈ 9.32 L
Therefore, there would be approximately 9.32 liters of radon gas in 3.43 moles at standard temperature and pressure.
Fe2O3 (molar mass = 159.7 g/mol) reacts with CO (molar mass = 28.0 g/mol) according to the equation When 125.6 g of CO reacts with excess Fe2O3, how many moles of Fe (iron) will be produced?
Answer:
=1.4953 moles
Explanation:
Iron (III) Oxide is reduced by carbon (II) oxide into Iron. According to the following equation, One mole of Fe₂O₃ react with 3 moles of CO to produce 2 moles of Fe. Thus the reaction ratio of CO to Fe₂O₃ is 3:1
Fe₂O₃₍s₎ + 3CO → 2Fe₍s₎ + 3CO₂₍g₎
125.6 grams of CO is equivalent to: 125.6g/28.0g/mol
=4.486 moles.
The number of moles of Fe produced by the reaction is:
=(4.486 moles×1)/3
=1.4953 moles
Chen drew a diagram to compare the ways in which different organisms obtain nitrogen. Which label belongs in the area marked z?
Answer:
Soil
Explanation:
Plants(a.k.a. Producers) obtain nitrogen(N) from the soil by absorption through their roots.
Answer:
D
Explanation:
Determine what is missing from this neutralization reaction: −−−−+KCl→AgCl+KNO3
A. Ag2KN
B. AgNO3
C. KN2O
D. NHO3
Answer:
B. AgNO₃
Explanation:
If the products contain Ag, Cl, K, and NO₃, then this means that these were also the reactants. Remember that matter cannot be created nor destroyed in a chemical reaction, so whatever elements in the reactants were used, would be found in the products. In other words, an element does not change into another.
AgNO₃ + KCl → AgCl + KNO₃
Which molecular solid would have the highest melting point?
O
A. One with induced dipole attractions
O
B. One that has hydrogen bonding
O
C. One made of nonpolar molecules
O
D. One with dipole-dipole attractions
Answer:
Choice B. The solid with hydrogen bonding.
Assumption: the molecules in the four choices are of similar sizes.
Explanation:
Molecules in a molecular solid are held intact with intermolecular forces. To melt the solid, it is necessary to overcome these forces. The stronger the intermolecular forces, the more energy will be required to overcome these attractions and melt the solid. That corresponds to a high melting point.
For molecules of similar sizes,
The strength of hydrogen bonding will be stronger than the strength of dipole-dipole attractions.The strength of dipole-dipole attractions (also known as permanent dipole) will be stronger than the strength of the induced dipole attractions (also known as London Dispersion Forces.)That is:
Strength of Hydrogen bond > Strength of Dipole-dipole attractions > Strength of Induced dipole attractions.
Accordingly,
Melting point due to Hydrogen bond > Melting point due to Dipole-dipole attractions > Melting point due to Induced Dipole attractions.
Induced dipole is possible between all molecules.Dipole-dipole force is possible only between polar molecules.Hydrogen bonds are possible only in molecules that contain [tex]\rm H[/tex] atoms that are bonded directly to atoms of [tex]\rm F[/tex], [tex]\rm O[/tex], or [tex]\rm N[/tex].As a result, induced dipoles are the only force possible between molecules of the solid in choice C. Assume that the molecules are of similar sizes, such that the strengths of induced dipole are similar for these molecules.
Melting point in choice B > Melting point in choice D > Melting point in choice A and C.
Answer:
B. One that has hydrogen bonding
What kind of bond is the result of the transfer of an electron?
A. An ionic bond
B. A metallic bond
C. A covalent bond
D. A hydrogen bond
Answer:
Answer choice A
Explanation:
When an electron is transferred to another atom, both atoms involved become ions.
Determine the number of moles. 2.4x10^24 atoms of Fe
is mercury a solution
Answer:
No.
Explanation:
Mercury is not a solution. It is a detonator.
What does this equation, 2 C(s) + O 2(g) ® 2 CO(g), tell us?
A) the number of atoms of each kind in reactants and products is the same
B) carbon monoxide (CO) is a product
C) two atoms of carbon undergo reaction
D) all of these
Answer:
D. All of these.
Explanation:
For an equation to be balanced the number of atoms of each kind in the reactants and the products should be the same.
Then from this equation, CO is a product.
Last, two carbon atoms undergo reaction with the oxygen molecule for complete reaction to occur. Each atom combines with one oxygen atom.
Answer:
D) All of these
Explanation:
[tex]2 C(s) + O_2 (g) > 2 CO(g)[/tex]
Reactant side (Left side) Element Product side (Right side)
2 C 2
2 O 2
Balanced!!!
Balancing is making the number of atoms of each element same on both the sides (reactant and product side).
To find the number of atoms of each element we multiply coefficient × subscript
For example [tex]5 Ca_1 Cl_2[/tex] contains
5 × 1 = 5 ,Ca atoms and
5 × 2 = 10, Cl atoms
If there is a bracket in the chemical formula
For example [tex]3Ca_3 (P_1 O_4 )_2[/tex] we multiply coefficient × subscript × number outside the bracket.......... to find the number of atoms (Please note: 3 is the coefficient, and if there is no number given then 1 will be the coefficient )
So
3 × 3 = 9 , Ca atoms
3 × 1 × 2 = 6, P atoms
3 × 4 × 2 = 24, O atoms are present.
what is the equilibrium expression for the reatcion bellow
2SO3(g)<=>O2(g)+2SO2(g)
The equilibrium expression for the given reaction 2SO3(g) <=> O2(g) + 2SO2(g) is Ke = [SO₃]² / ([SO₂]² [O₂]).
Explanation:The equilibrium expression for the given reaction is Ke = [SO₃]² / ([SO₂]² [O₂]).
Ke represents the equilibrium constant, which is a measure of the extent to which a reaction reaches equilibrium. In this case, the equilibrium constant is calculated by taking the square of the concentration of SO₃ and dividing it by the product of the squares of the concentrations of SO₂ and O₂.
For example, if the concentrations at equilibrium are [SO₂] = 0.90 M, [O₂] = 0.35 M, and [SO₃] = 1.1 M, the value of the equilibrium constant, Ke, can be calculated as Ke = (1.1)² / ((0.90)² (0.35)).
2.18 Determine whether each of the following statements is
true or false; if false, correct the statement to make it
true: (a) The nucleus has most of the mass and compris-
es most of the volume of an atom; (b) every atom of a
given element has the same number of protons; (c) the
number of electrons in an atom equals the number of
neutrons in the atom; (d) the protons in the nucleus of
the helium atom are held together by a force called the
strong nuclear force.
(a) The nucleus has most of the mass and comprises most of the volume of an atom; false
The nucleus has most of the mass but the volume of an atom is depends on the distance between the nucleus and the position of the electrons.
(b) Every atom of a given element has the same number of protons; true
They may have different number of neutrons and so you have isotopes but the number of protons remain the same for a given element.
(c) The number of electrons in an atom equals the number of neutrons in the atom; false
The number of electrons in an atom equals the number of protons in the atom.
The electrons are negatively charged which compensate the positively charged protons not the neutrons which do not have a charge (they are neutral).
(d) The protons in the nucleus of the helium atom are held together by a force called the strong nuclear force. true
Answer:
(a) False
(b) True
(c) False
(d) True
Explanation:
Option A is false. The nucleus has most of the mass in a small volume thus making it very dense. But the volume is given by the atomic radius that is the distance between the center of the nucleus and the electrons in different atomic orbitals.
Option B is true. Every atom of an element has the same atomic number. Atomic number is the total number of protons in an atom.
Option C is false. In a neutral atom the number of electrons is equal to the number of protons. Neutrons are neutral in charge.
Option D is true. All protons are positively charged and similar charges repel each other with electrostatic forces of repulsion but the nuclear forces overcome the repulsive forces and stabilize the protons in the nucleus of the atom.
An atom of boron has an atomic number of 5 and an atomic mass of 11. The atom contains
5 protons, 6 electrons, and 5 neutrons.
11 protons, 11 electrons, and 5 neutrons.
5 protons, 5 electrons, and 6 neutrons.
11 protons, 6 electrons, and 6 neutrons.
Answer:
5 protons, 5 electrons, and 6 neutrons
An atom of boron has 5 protons, 5 electrons, and 6 neutrons. This composition aligns with its atomic number of 5 and an atomic mass of 11. Therefore, the correct option is the one with 5 protons, 5 electrons, and 6 neutrons.
To determine the composition of a boron atom, we need to understand the concepts of atomic number and atomic mass. Boron has an atomic number of 5, which means it has 5 protons. The atomic mass of boron is approximately 11, which is the sum of the number of protons and neutrons.
Given these details, the correct configuration of a boron atom with an atomic number of 5 and an atomic mass of 11 is:
5 protons5 electrons6 neutronsThus, an atom of boron has 5 protons, 5 electrons, and 6 neutrons. This corresponds to the configuration that meets both the atomic number and atomic mass criteria as mentioned earlier.
Which of the following types of energy does an object have because of its motion?
Chemical energy
Gravitational energy
Kinetic energy
Potential energy
Answer: Kinetic energy
Explanation:
Chemical energy is the energy stored in the bonds of molecules.
Gravitational energy is the potential energy held by an object because of its higher position compared to a lower position.
Kinetic energy is the energy possessed by a body by virtue of its motion.
Potential energy is the energy possessed by a body by virtue of its position.
Thus kinetic energy is the energy associated with an object because of its motion.
Imagine you are a detective examining a crime scene. You are trying to
identify the person who committed the crime, so you collect many samples at
the crime scene. Which sample would be most useful in identifying the
person who committed the crime?
O
A. A newspaper left at the crime scene
O
B. An ant found crawling across the crime scene
O
C. Pieces of hair found at the crime scene
O
D. Gravel and dirt on the ground at the crime scene
SUBMIT
Answer:
C. pieces of hair found at the crime scene.
Explanation:
using the pieces of hair, you can get the DNA of the person. This will give u a better lead in solving the crime.
Hope it helps u ....
Answer:
C. Pieces of hair found at the crime scene.
Explanation:
Pieces of hair found at the crime scene is more useful to find the criminal who committed the crime, because it helps in indetifying criminal's DNA through the process of DNA fingerprinting. The hair is analyzed by the chemical makeup of the hair and extracting DNA from the hair follicle, pieces of hair must have hair follicle attached to find DNA of the criminal.
Nuclear DNA can be successfully extracted from the hair root. Cut hair samples are useless without hair follicle attached. Its DNA will be useful only few months for testing. The DNA last in hairs about 1,000 to 10,000 years.
Please help me! I think the answer to this is C because gas produced from liquid has the greatest release in entropy, right? And C is the only option producing gas. Please help me out! Is C the right answer or which one is?
The systems that shows the greatest increase in entropy is -
a.2H2 + O2®2H2O
b.NaCl ®Na+1 + Cl-1
c.2H2O ®2H2 + O2
d.AgCl3®Ag+3 + 3Cl-1
Answer:
c. 2H₂O → 2H₂ + O₂
Explanation:
Entropy is the state of randomness or disorderliness of the particles of a system. The more random and disorderly a system is, the more its entropy. When the physical state of matter changes, there is a considerable change in the entropy of such a system.
The increasing order of entropy is as listed below:
Solid < liquid < gas
Gases have the highest randomness in all states of matter.
From the equation of the reaction in option C, we see that water is going into the gaseous phase. The products of the reaction are hydrogen and oxygen gases. This is an increase in entropy.
Reaction B and D produced ions which are in aqeous solutions. They move from originally solid sate to a liquid phase.
Reaction A takes gases and turns them into water. This is a decrease in entropy.
Which of the following are dipole-dipole interactions that occur only between molecules containing N-H, O-H or F-H bonds?
Ion-dipole forces
Hydrogen bonding
Dipole-dipole forces
London dispersion forces
Answer:
Hydrogen bonding
Explanation:
Hydrogen bonds are special dipole-dipole attraction between polar molecules in which a hydrogen molecule atom is directly joined to a highly electronegative atom.
This type of bond is an intermolecular bond caused by an electrostatic attraction between the hydrogen atom of one molecule and the electronegative atom(O or N or F) of a neighbouring molecule.
Answer:
Hydrogen bonding
Explanation:
Hydrogen bonding is a type of dipole dipole interaction. It exist between H atom bonded to electronegative atom; O, N, F and other O, N, F of another molecule.
Some of the examples of compounds having hydrogen bonding are:
[tex]NH_3,\ H_2O,\ HF,\ CH_3OH,\ etc.[/tex]
Hydrogen bonding exists because of development of dipole dipole interaction between H and electronegative atom.
As H is less electronegative as compared to O, N and F. So partial positive charge develop on H and partial negative chagre develop develop on the attached electronegative atom. Because of development of partial positive and partial negative charge, dipole dipole interaction occurs which leads to the development of hydrogen bonding.