Answer:
The 5R's are Reuse, Reduce, Recycle, Repair and Recover.
evidence of a chemical change includes?
Answer:
Change of color, change in temperature, change of energy or loss heat, odor etc....
In which orbitals would the valence electrons for carbon (C) be placed?
Answer: orbitals supernumerary
Explanation:
Answer:
both S orbital and p orbitals
Explanation:
took the exam got the question right.
Which structure below contains all of the others?
DNA
gene
chromosome
nucleus
Answer:
nucleus
Explanation:
The nucleus holds all the other things, keeping them safe and confined.
Answer:
Nucleus
Explanation:
It contains DNA which contains a GENE which contains a CHROMOSOME so its NUCLEUS
S
Perform the following operation
and express the answer in
scientific notation.
1.248x10-2 : 7.8x10-7
[? ]x10
Answer: [tex]1.6\times 10^4[/tex]
Explanation:
Scientific notation is defined as the representation of expressing the numbers that are too big or too small and are represented in the decimal form with one digit before the decimal point times 10 raise to the power.
For example : 5000 is written as [tex]5.0\times 10^3[/tex]
In division , the result would contain the same number of significant digits as there in the least precise number , thus the answer would have 2 significant digits.
[tex]\frac{1.248\times 10^{-2}}{7.8\times 10^{-7}}=1.6\times 10^4[/tex]
how can you tell from the name the types of bonds present in a hydrocarbon?
Answer:
Alkane
Alkene
Alkyne
Explanation:
Alkane=1 bond (Saturated hydrocarbon)
Alkene= 2 bonds (Unsaturated hydrocarbon)
Alkyne= triple bonds (Unsaturated hydrocarbon)
Formula of Alkane = CnH2n+2
Formula of Alkene = CnH2n
Formula of Alkyne = CnH2n-2
When electrons are removed from the outermost shell of a calcium atom, the atom becomes
A)an anion that has a larger radius than the atom.
B) an anion that has a smaller radius than the atom.
C)a cation that has a larger radius than the atom.
D) a cation that has a smaller radius than the atom.
Answer:
A cation that has a smaller radius than the atom.
Explanation: when electrons are removed from the outermost shell of a calcium atom, the atom becomes a cation that has a smaller radius than the atom.
When electrons are removed from the outermost shell of a calcium atom, the atom becomes a cation that has a smaller radius than the atom. Therefore, the correct option is option D.
What is atom?Atom, the smallest unit of matter that may be separated without releasing electrically charged particles. It is also the smallest unit of matter with the characteristics of a chemical element. As a result, the atom is indeed the fundamental building component of chemistry.
The majority of the atom comprises empty space. The rest of the structure is made up of a positive-charged nucleus of neutrons and protons surrounding by a cloud of electrons with negative charges. In comparison to electrons, the lightest energized particles in nature, the nuclei is small and dense. When electrons are removed from the outermost shell of a calcium atom, the atom becomes a cation that has a smaller radius than the atom.
Therefore, the correct option is option D.
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Give some examples of how ultraviolet rays can be used
Answer:
One of the most common ways of producing UV light is passing an electric current through vaporized mercury or some other gas. This type of lamp is commonly used in tanning booths and for disinfecting surfaces. The lamps are also used in black lights that cause fluorescent paints and dyes to glow.Explanation:
How much cesium (half-life = 2 years) would remain from a 10 g sample after
4 years?
O A. Og
OB. 8g
O c. 59
O D. 29
SUBMIT
Answer: 2.5 grams
Explanation:
Expression for rate law for first order kinetics is given by:
[tex]t=\frac{2.303}{k}\log\frac{a}{a-x}[/tex]
where,
k = rate constant
t = age of sample
a = let initial amount of the reactant
a - x = amount left after decay process
a) to calculate the rate constant:
Half life is the amount of time taken by a radioactive material to decay to half of its original value.
[tex]t_{\frac{1}{2}}=\frac{0.693}{k}[/tex]
[tex]k=\frac{0.693}{2years}=0.346years^{-1}[/tex]
b) to find amount left after 4 years
[tex]4=\frac{2.303}{0.346}\log\frac{10}{a-x}[/tex]
[tex](a-x)=2.5g[/tex]
Thus 2.5 g of cesium would remain from a 10 g sample after 4 years
What is the total energy change for the following reaction: H2 + I2 -> 2HI?
Given:
H-H bond: 436 kJ/mol
I-I bond: 151 kJ/mol
H-I bond: 297 kJ/mol
A. +7 kJ/mol
B. +297 kJ/mol
C. -290 kJ/mol
D. -7 kJ/mol
Energy change is the conversion of the energy stored in reactants to products. In the reaction between hydrogen and iodine, the energy change is -7 kJ/mol. Thus, option D is correct.
What is total energy change?Total energy change is the conversion of the energy from a substance to another when the reactant undergoes modification to produce a product.
The reaction is given as,
H₂ + I₂ → 2HI
In the reaction, the bonds between H-H and I-I are broken to release energy that produces two H-I bonds as the product.
Given,
H-H bond = 436 kJ/mol
I-I bond = 151 kJ/mol
H-I bond = 297 kJ/mol
So, 436 kJ/mol + 151 kJ/mol - 2x297 kJ/mol = -7 kJ/mol
Therefore, -7 kJ/mol is the total energy change in the reaction involving hydrogen and iodine.
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what is the difference between an exothermic and endothermic reaction.
Answer:
An endothermic reaction takes in heat, but feels cold to the touch. An exothermic reaction gives off heat and feels warm to the touch because it is heating the outside objects.
polarity of the molecules increase with electro nogativity
Answer:
true
Explanation:
polarity of the molecules increased with electronegatiy it's true
Which of the following is true about the principle of the conservation of mass? *
1 point
d. The mass of the products is never equal to the mass of the reactants.
e. The mass of the products is less than the mass of the reactants.
f. The mass of the products is equal to the mass of the reactants.
g. The mass of the products is greater than the mass of the reactants.
Answer:
F
Explanation:
"The mass of the products is equal to the mass of the reactants" is true about the principle of the conservation of mass.
So, option f is correct one.
What is the principle of conservation of mass?The principle of the conservation of mass states that mass can neither be created nor be destroyed in a chemical reaction, it only transferred from reactants to products. It means that mass of reactants is equal to mass of products.Example when wood burns the mass of shoot, ashes, and gases equal to the original mass of of charcoal and oxygen when it first react.To learn more about conservation of mass here.
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Builders and dentists must store plaster of Paris,
CaSO4 x 1/2 H2O, in airtight containers to prevent it from
absorbing water vapor from the air and changing to
gypsum, CaSO4 x 2H2O How many liters of water
vapor evolve when 2.00 kg of gypsum are heated at
110°C to produce plaster of Paris? At 110°C, the
density of water vapor is 0.574 g/L.
In order to determine the amount of water that evaporates from we need to convert the mass into volume.
What temperate is required to produce the POP ?The builders and the density use the plaster of Paris called POP and are a CaSO4 x 1/2 H2O is used for the airtight containers to stop them from taking in water vapors from the air and changes into gypsum that is CaSO4 x 2H2O. The answer is given as below. Answer:
The plaster of Paris is used for coating the walls and the celling from the aspects of molding. Its also used for casting decorative elements.
It absorbs water from the air and vapor evolves when the 2.00 kg of gypsum is heated at 110 degrees. C.
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Question 11
A solution cannot dissolve any more solute even though only a small amount of solute has
been added to the solvent. This solution is
1. saturated and concentrated
2. unsaturated and dilute
3. saturated and dilute
4. unsaturated and concentrated
Answer:
Explanation:
B.) Saturated
A saturated solution is when the maximum amount of solute that could be dissolved in that solvent volume at that temperature and pressure has been dissolved, adding more solute beyond this point would lead to the additional solute not dissolving in the solvent. When the maximum solute concentration in the solution that can be dissolved has been reached the solution is said to be saturated.
Hope This Helps??
what is electrolysis
Answer:
electrolysis is a technique that uses a direct electric current to drive an otherwise non-spontaneous chemical reaction
Explanation:
Please answer number 5 ASAP
Answer: Hello mister i dont now your question
Explanation:
which substance will form a solution when mixed with liquid benzene (c6h6)
Answer: [tex]I_{2} (l)[/tex]
Explanation: Because C 6 H 6 is nonpolar substance and I 2 is also nonpolar compound
According to the concept of solubility,iodine will form a solution when mixed with liquid benzene as both are non-polar substances.
What is solubility?Solubility is defined as the ability of a substance which is basically solute to form a solution with another substance. There is an extent to which a substance is soluble in a particular solvent. This is generally measured as the concentration of a solute present in a saturated solution.
The solubility mainly depends on the composition of solute and solvent ,its pH and presence of other dissolved substance. It is also dependent on temperature and pressure which is maintained.Concept of solubility is not valid for chemical reactions which are irreversible. The dependency of solubility on various factors is due to interactions between the particles, molecule or ions.
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to well
Which of the
of the following is a way to use
water economically
a construction of bewris
b Rainwater harvesting
c Drup irrigation
d Infitration
Answer:
c Drup irrigation
Explanation:
Hope it helps you.
Plz mark as brainliest plz.
What is a chemical solution and what are the names of its components?
Answer:
A chemical solution is defined as a homogeneous mixture of two or more substances. There are two components of chemical solution that include solute and solvent.
Solute is the component that get dissolved in another substance and solvent is the substance that dissolve solute.
For example: carbon dioxide in water. Where carbon-dioxide is solute and water is solvent.
⚠️SOMEONE PLEASE HELP⚠️
Which describes two phases in dynamic equilibrium?
O A. Molecules in one phase continually change to the other.
O B. The total number of molecules must be equal in each phase.
O C. Molecules do not change from one phase to the other.
O D. The total number of molecules in each phase stays constant.
Answer:
The total number of molecules in each phase stays constant
Explanation:
i just took the test and got it right.
In the dynamic equilibrium between 2 phases, the total number of molecules in each phase stays constant (Option D).
When does dynamic equilibrium occur?Dynamic equilibrium occurs when the direct and reverse rates are equal and the concentrations remain constant over time.
Which describes two phases in dynamic equilibrium?
A. Molecules in one phase continually change to the other. NO. Molecules in both phases continually change.B. The total number of molecules must be equal in each phase. NO. This is not necessarily true.C. Molecules do not change from one phase to the other. NO. This would be a static equilibrium.D. The total number of molecules in each phase stays constant. YES. Since the forward and reverse rates are equal.In the dynamic equilibrium between 2 phases, the total number of molecules in each phase stays constant (Option D).
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can a substance be a lewis acid without being a bronsted-lowry acid?argue
Answer:
Yes
Explanation:
Yes, A substance can be a lewis acid without being a Bronsted-Lowery acid because there are some substances which cannot donate protons(Bronsted-Lowery acid) but can accept a pair of electron.
For Example:
Let us take the example of BF₃
BF₃ contains no proton so it is not a Bronsted Lowery Acid
However, BF₃ has an incomplete octet with 6 electrons. It needs an electron pair to complete its octet. It accepts a pair of electron to become a Lewis Acid
Answer:
Interesting question, and the answer is yes, a substance can be a Lewis acid but not a Bronsted-Lowrey acid. To see this, let’s take a look at the definitions of each.
Explanation:
Bronsted-Lowrey acid:
A compound that is a hydrogen ion (proton) donor. When dissolved in the solvent in question, these compounds lose a proton to the solution. The concentration of these protons in solution is referred to as acidity, and is measured on the pH scale.
Lewis acid:
A substance that is an electron pair receiver. In solution, free electron pairs will form bonds with the substance, either ionic or covalent. In this definition, a proton is itself an acid, rather than a part of an acid.
A key thing to note here is that, in the Bronsted-Lowrey definition, there must be a proton. That means, all Bronsted-Lowrey acids are of the form HXn→H++Xn− , showing the dissociation in solution. However, a Lewis acid needs only to have the ability to accept an electron pair, which means that H+ is a Lewis acid, instead of what makes a compound an acid. Additionally, that means that the number of compounds that qualify as a Lewis acid are expanded. A favorite example of mine is boron trifluoride, or BF3 . It is a common reagent in organic synthesis, it is a Lewis acid, but does not have any hydrogen, so it cannot be a Bronsted-Lowrey acid
In the following reaction, which are the products?
Mg + 2HCl —> H2 + MgCl2
If you could, please explain as well.
Answer: H2 + MgCl2
Explanation: As they are on the right side of the equation/ are the products being made as a result of the reaction, they are the products.
What is the frequency of radiation emitted by a photon of light if the energy released during its transition to ground state is 3.611 × 10-15 joules? (Planck's constant is 6.626 × 10-34 joule seconds)
Answer:
5.449 x 10¹⁸ Hz
Explanation:
Energy (E) =Frequency (F) x Plancks constant (h)
F= 3.611x10⁻¹⁵J / 6.626 x 10⁻³⁴ Js⁻¹
F =5.449 x10¹⁸ s⁻¹ or 5.449 x 10¹⁸ Hz
The melting point of three solids X,Y and Z are 298K, 314 K and 398K respictively.Arrange these in increasing order of their inter particle force of attraction
Answer:
Explanation:
The higher the melting point of a substance, then the higher the force of attraction. Which means there is direct relationship between the melting point and force of attraction.
The increasing order of interparticle force of attraction of the the three particles are
Z(398) Y(314) X (298)
I.e Particle " Z " have highest melting point, follows by particle "Y" follows by particle "X
NOTE: The melting point of a substance refers to the
temperature whereby there there is a change from solid state to liquid state, it is dependent on the pressure of the system
The octane number of fuel is 79%. What does that mean
Answer:
Octane number, measure of the ability of a fuel to resist knocking when ignited in a mixture with air in the cylinder of an internal-combustion engine.
Octane number is also known as octane rating. Octane numbers are based on a scale on which isooctane is 100 (minimal knock) and heptane is 0 (bad knock). The higher the octane number, the more compression required for fuel ignition. Fuels with high octane numbers are used in high performance gasoline engines.
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Given the formula representing a compound: What is the IUPAC name of this compound?
Answer:
2,2- dichloro-heptane
Explanation:
The IUPAC name of the compound is 2,2-dichloro-heptane
How many atoms or molecules are in 5.0 moles of the following?
a. O
b. N
c.MgCl₂
d. C₂H₃NO
Answer:
They all have the same number of molecules or atoms which is 3.011*10²⁴ molecules or atoms.
5 moles of O = 3.011*10²⁴ molecules or atoms
5 moles of N = 3.011*10²⁴ molecules or atoms
5 moles of MgCl2 = 3.011*10²⁴ molecules or atoms
5 moles of C2H3NO = 3.011*10²⁴ molecules or atoms.
Explanation:
a)
5 moles of O = ?
1 mole of any substance is equal to Avogadro's number which is equal to 6.022×10²³molecules or atoms
From the question above,
5 moles of O = 5 × 6.022*10²³ = 3.011×10²⁴atoms or molecules.
b)
5 moles of N
From the same principle or fundamentally stated fact above,
1 mole of any substance = 6.022*10²³molecules or atom
5 moles of N = 5 × 6.024
2*10²³ = 3.011*10²⁴atoms or molecules.
c)
5 moles of MgCl₂
Same principle we used in a and b,
1 mole of any substance = 6.022*10²³ atoms or molecules
5 moles of MgCl2 = 5.0×6.022*10²³ = 3.011*10²⁴ atoms or molecules.
d)
5 moles of C₂H₃NO = ?
1 mole of C₂H₃NO = 6.022*10²³molecules or atoms
5 moles = x molecules or atoms
x = 5 × 6.024
2*10²³ = 3.011*10²⁴ atoms or molecules
What this proves is that no matter the compound, molecule or element, as long as they have equal amount of moles, they'll have the same number of atoms, molecules or particles.
Answer:
a. 3.011x10²⁴ atoms of O in 5 moles.
b. 3.011x10²⁴ atoms of N in 5 moles.
c. 3.011x10²⁴ atoms of MgCl₂ in 5 moles.
d. 3.011x10²⁴ atoms of C₂H₃NO in 5 moles
Explanation:
A mole is defined as the number of atoms in exactly 12.000g of ¹²C.
This number is equal to 6.022x10²³. That means 1 mole is equal to 6.022x10²³.
Thus:
a. O . 5 moles of oxygen (An atom) are:
5 moles O ₓ (6.022x10²³ atoms of O / mole) = 3.011x10²⁴ atoms of O in 5 moles
b. N . Also, 5 moles of nitrogen are:
5 moles N ₓ (6.022x10²³ atoms of N / mole) = 3.011x10²⁴ atoms of N in 5 moles
c. MgCl₂ . Magnesium chloride is a molecule. Again, 1 mole of MgCl₂ contains 6.022x10²³ molecules and 5 moles are:
5 moles MgCl₂ ₓ (6.022x10²³ molecules of MgCl₂ / mole) = 3.011x10²⁴ atoms of MgCl₂ in 5 moles
d. C₂H₃NO. 5 moles of C₂H₃NO are:
5 moles C₂H₃NO ₓ (6.022x10²³ molecules of C₂H₃NO / mole) = 3.011x10²⁴ atoms of C₂H₃NO in 5 moles
As you can see, number of molecules of 1 mole doesn't depend on the nature of the substance.
How many grams of chlorine gas are needed to react with 3.5 liters of a 1.7 molar
potassium bromide solution?
Cl2 + 2 KBr - 2 KCl + Br2
Answer: 211.2 grams
Explanation:
To calculate the number of moles for given molarity, we use the equation:
[tex]\text{Molarity of the solution}=\frac{\text{Moles of solute}}{\text{Volume of solution in L)}}[/tex] .....(1)
Molarity of [tex]KBr[/tex] solution = 1.7 M
Volume of solution = 3.5 L
Putting values in equation 1, we get:
[tex]1.7M=\frac{\text{Moles of}KBr}{3.5L}\\\\\text{Moles of }KBr=\{1.7mol/L\times 3.5L}=5.95moles[/tex]
The balanced chemical reaction is:
[tex]Cl_2+2KBr\rightarrow 2KCl+Br_2[/tex]
According to stoichiometry:
2 mole of KBr requires = 1 mole of [tex]Cl_2[/tex]
5.95 moles of KBr requires = [tex]\frac{1}{2}\times 5.95=2.975[/tex] moles of [tex]Cl_2[/tex]
Mass of [tex]Cl_2=moles\times {\text {Molar mass}}=2.975mol\times 71g/mol=211.2g[/tex]
Thus 211.2 grams of chlorine gas are needed to react with 3.5 liters of a 1.7 molar potassium bromide solution
Which one is NOT an acid?
A. H2S04 B. H2NO3 C. HCI D. NaOH
The sodium salt, NaA, of a weak acid is dissolved in water; no other substance is added. Which of these statements (to a close approximation) is true?
Answer:
Your question is somewhat poorly worded, even so what I can contribute is the statement is false, since the salt is sodium chloride, where its severe chemical formula NaCl, is a SALT not an acid and if it dissolves in water, seriously the solute of a solution, where water plays the role of the solvent
Explanation:
Sodium chloride is a binary salt, very easy to dissolve in water, it is also called the famous table salt, since it can be ingested in food even though it is not so recommended against high blood pressure conditions.
