Answer:
Evolution in the broadest sense explains that what we see today is different from what existed in the past. Galaxies, stars, the solar system, and earth have changed through time, and so has life on earth.Something that happened in the past is thus not "off limits" for scientific study. Hypotheses can be made about such phenomena, and these hypotheses can be tested and can lead to solid conclusions. Furthermore, many key aspects of evolution occur in relatively short periods that can be observed directly—such as the evolution in bacteria of resistance to antibiotics.Laws, like facts and theories, can change with better data. But theories do not develop into laws with the accumulation of evidence. Rather, theories are the goal of science.
Explanation:
If the half-life of a decaying isotope is 10 years, which statement is true after
20 years?
Answer:
A. There are more daughter nuclei than parent nuclei in a sample.
Explanation:
There are more daughter nuclei than parent nuclei in a sample. Hence, option A is correct.
What is half-life?The half-life of a radioactive element or isotope is the time taken for half of the substance to decay.
If the half-life of a decaying isotope is 10 years, after 8 years, less than the total mass of the original isotope will decay since 8 years is less than 10 years.
Therefore, we can conclude that, if the half-life of a decaying isotope is 10 years, after 8 years, there will be more parent nuclei than daughter nuclei in a sample.
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The enthalpy (AH) is +624.7 kJ for the following reaction. How would you classify this reaction? (Explain)
SiO2(g) + 3C(s) --> SIC(s) +2CO(g)
A.exothermic: heat is lost by the system
B.endothermic: heat is gained by the system
C.endothermic: heat is lost by the system
D.exothermic: heat is gained by the system
Answer: The reaction [tex]SiO_{2}(g) + 3C(s) \rightarrow SiC(s) + 2CO(g); \Delta H = +624.7 kJ[/tex] is classified as endothermic: heat is gained by the system.
Explanation:
A process or reaction in which heat is absorbed is called endothermic reaction.
For example, melting of ice is an endothermic process.
For an endothermic reaction the sign of [tex]\Delta H[/tex] is positive which means heat is gained by the system.
Here, the given reaction is as follows.
[tex]SiO_{2}(g) + 3C(s) \rightarrow SiC(s) + 2CO(g); \Delta H = +624.7 kJ[/tex]
A process or reaction in which heat is released is called exothermic reaction.
For example, combustion reaction, freezing of water etc are exothermic process.
For an exothermic reaction the sign [tex]\Delta H[/tex] is negative which means heat is lost by the system.
Thus, we can conclude that the reaction [tex]SiO_{2}(g) + 3C(s) \rightarrow SiC(s) + 2CO(g); \Delta H = +624.7 kJ[/tex] is classified as endothermic: heat is gained by the system.
What is the best explanation for the fact that Styrofoam will not dissolve in water, but Styrofoam will dissolve in acetone?
1.styrofoam is polar and water is nonpolar
2.styrofoam is nonpolar and water is polar
3.Styrofoam is polar and water is polar
4.styrofoam is nonpolar and water is nonpolar
What can we do to protect our oceans ?
what is Nylon 6-6 made of..?
Answer:
nylon 66 is made of two monomers each containing 6 carbon atoms, hexamethylenediamine and adipic acid.
Which forward reaction shows an increase in entropy (disorder)?explain
A.H2(g) + CuO (s) --> H2O(l) + Cu(s)
B.HCl(g) + NH3(g) --> NH4Cl(s)
C.CaCO3(s) -> CaO(s) + CO2g)
D.H2O(g) + O2(g) --> 2H2O)
Explanation:
Entropy also increases when solid reactants form liquid products. Entropy increases when a substance is broken up into multiple parts. The process of dissolving increases entropy because the solute particles become separated from one another when a solution is formed. Entropy increases as temperature increases. S = entropy
k_{b} = Boltzmann constant
\ln = natural logarithm
\Omega = number of microscopic configurations
Should American drugmakers have to limit acetaminophen pills sold over-the-counter?
Answer: The agency requires all prescription drugs containing acetaminophen to carry a black box warning that an overdose can result in liver transplant or death. For over-the-counter Tylenol and its generic equivalents, the FDA requires no warning that overdose can be fatal.
Explanation:
^^^^
Which type of circuit has more than one path?
Answer:
parallel circuit
Explanation:
Hope this is right!!
When two atoms form a molecule, the molecule has lower energy than the two separate atoms. However, when only two atoms are present, they bounce off each other and do not form a molecule. Explain what happens to the energy of the atoms when there are only two atoms and they collide.
DONT GIVE ME A LINK!!
Answer:
they end up bouncing against each other instead of merging together
Explanation:
What is the connection between iozination energy, electronegativity, and electron affinity of elements
Answer:
Explanation:
The three of them increase from left to right across the periods of the periodic table, and at the same time, they decrease from up to down across the groups of the periodic table.
Ionization Energy is defined as the energy required to remove the atom of an electron.
Electron affinity is defined as the change in energy when electron is added to a negative ion.
Electronegativity is the ability of an atom to attract other atoms to itself.
What causes the "heat island" effect?
a. heat produced from a large number of people
b. the materials used in building cities retain heat
c. the large amount of reflected light from glass windows
d. all of the above
Please select the best answer from the choices provided
A
B
C
D
2 H2(g) + O2 (g) --> 2 H20 (1)
How many moles of hydrogen gas do you need to make 2 moles of liquid water?
Answer:
4moles of hydrogen atoms
Explanation:
The second conversion factor reflects the number of atoms contained within each molecule. Two water molecules contain 4 hydrogen atoms and 2 oxygen atoms. A mole of water molecules contains 2 moles of hydrogen atoms and 1 mole of oxygen atoms.
what are the 5 similarities between acid and alkalis
Explanation:
Acids and alkalis both contain ions. Acids contain lots of hydrogen ions, which have the symbol H+. Alkalis contain lots of hydroxide ions, symbol OH-. Water is neutral because the number of hydrogen ions is equal to the number of hydroxide ions
Answer:
cids and bases both react with water and a lot of acids and bases are soluble in nature. Both acids and bases are electrolytes which means that they're good conductors of electricity. Acids and bases both produce ions in water solution. Acids release hydrogen ions (H+) whereas Bases release hydroxide ions (OH–).
Explanation:
grade 8 chem/ science
Answer:
reactants
Explanation:
have a good day!
What volume would be occupied by 16.0 g of CH4 at 00C and 760 mmHg?
Answer:
22.4 L
Explanation:
We'll begin by calculating the number of mole in 16.0 g of CH₄. This can be obtained as follow:
Molar mass of CH₄ = 12 + (4×1)
= 12 + 4
= 16 g/mol
Mass of CH₄ = 16 g
Mole of CH₄ =?
Mole = mass / molar mass
Mole of CH₄ = 16 / 16
Mole of CH₄ = 1 mole
Finally, we shall determine the volume of the gas. This can be obtained as follow:
Number of mole of CH₄ (n) = 1 mole
Pressure (P) = 760 mmHg = 1 atm
Temperature (T) = 0°C = 273 K
Gas constant (R) = 0.0821 atm.L/Kmol
Volume (V)?
PV = nRT
1 × V = 1 × 0.0821 × 273
V = 22.4 L
Therefore, the volume of the gas is 22.4 L
Calculate the potential energy of a block of mass of mass 0.3kg and at a height 2.6m above the ground.(take acceleration due to gravity:10m/s)
Explanation:
Mass (m)=0.3 kg
height(h)=2.6 m
acceleration due to gravity (g)=10m/s^2
Potential energy= MGH
=0.3×10×2.6
7.8 J
Give brainliest if u can
Magnesium metal reacts with oxygen according to the equation: Mg(s) + O2(g) → 2MgO2(s)
Which of the following would increase the rate of the reaction?
grinding the magnesium metal into a fine powder
packing the magnesium tightly at the bottom of the container
forming the magnesium metal into the shape of a sphere
forming the magnesium metal into single, large cube
Answer:
Grinding the magnesium metal into a fine powder. I took the test and got it right.
If you hear a weather report say that a low pressure system is coming in, what kind of weather can you expect?
A
wind
B
polluted air
C
precipitation
D
heat
What type of erosion and deposition is not a major force in Texas
Select the correct answer.
A compound has an empirical formula of C2H5. What is true about this empirical formula?
ОА It models the structure of the compound.
ОВ. It shows the ratio of elements in the compound.
Ос. . It gives the mass of each atom in the compound.
OD. It indicates the number of atoms in the compound.
O E. It describes only this one compound.
Answer: OB
Explanation:
The empirical formula of an element is the simplest formula of an element which shows the ratios of atoms of the each element present in a molecule of a compound .
What type of molecule is shown below?
H H
| |
H-C-C-0-H
|
Η Η
A. Ether
B. Aldehyde
C. Ketone
D. Alcohol
The type of molecule which is shown in the given question is alcohol, due to presence of hydroxyl group.
What are functional groups?Funcional groups are those specific groups which after attaching to any compound changes the property of that compound and then that compound will known by the propeties of that functional group.
Given molecule has the molecular structure CH₃-CH₂-OH, means in this molecule hydroxyl group is present which defines the general properties of alcohol.
Hence given molecule is an alcohol.
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Awnser all of them if you can its really EASY im feelin generous today 30 pts
Answer: 1. Synthetic Substance or Synthetic compound 2. Oil 3. Biofuels 4. Salt and Sugar 5. medicine 6. Synthetic 7. Background Knowledge and Visualizing
Explanation: Hope this helps! Good luck!
Answer:
1= synthetic substance
2= natural gas
3= alcohol
4=artificial musks
5= medicine
6= synthetic
7=Questioning the Text
Explanation: If my answers are correct please mark me as a brainlist.
How much energy is required to raise the temperature of a 300.0
gram block of lead from 22.3°C to 59.9°C? The specific heat of lead is
0.129 J/gºC.
Answer:
Q = 1455.12 Joules.
Explanation:
Given the following data;
Mass = 300 grams
Initial temperature = 22.3
Final temperature = 59.9°C
Specific heat capacity = 0.129 J/gºC.
To find the quantity of energy;
[tex] Q = mcdt[/tex]
Where,
Q represents the heat capacity.
m represents the mass of an object.
c represents the specific heat capacity of water.
dt represents the change in temperature.
dt represents the change in temperature.
dt = T2 - T1
dt = 59.9 - 22.3
dt = 37.6°C
Substituting the values into the equation, we have;
[tex] Q = 300*0.129*37.6 [/tex]
Q = 1455.12 Joules.
2.91 moles of aluminum are how many grams(with work)
The Lewis diagram for AlF3 is:
:F:
The electron-pair geometry around the Al atom in AlF3 is
There is/are
lone pair(s) around the central atom, so the geometry of AlF3 is
Submit Answer
Retry Entire Group
9 more group attempts remaining
Answer:
25,000 pairs
Explanation:
What is the number of moles of Sodium Chloride (NaCl) that is present in 29.22g sample of it?
Answer:
[tex]\boxed {\boxed {\sf 0.5000 \ mol \ NaCl}}[/tex]
Explanation:
We are asked to convert grams to moles. We must use the molar mass or the grams in 1 mole of a substance. These values are found on the Periodic Table as the atomic mass, but the units are grams per mole (g/mol) instead of atomic mass units (amu).
We are given the compound sodium chloride or NaCl. Look up the molar masses of the individual elements.
Na: 22.9897693 g/mol Cl: 35.45 g/molThe formula for the compound does not contain any subscripts, so there is 1 mole of each element in 1 mole of the compound. Add the molar masses together to find sodium chloride's molar mass.
NaCl: 22.9897693 + 35.45= 58.4397693 g/molNow we can use the molar mass to create a ratio. We know there are 58.4397693 grams of NaCl in 1 mole of NaCl.
[tex]\frac {58.4397693 \ g \ NaCl}{ 1 \ mol \ NaCl}[/tex]
Multiply by the number of grams provided in the problem: 29.22
[tex]29.22 \ g\ NaCl*\frac {58.4397693 \ g \ NaCl}{ 1 \ mol \ NaCl}[/tex]
Flip the ratio so the units of grams of NaCl cancel.
[tex]29.22 \ g\ NaCl*\frac { 1 \ mol \ NaCl}{58.4397693 \ g \ NaCl}[/tex]
[tex]29.22*\frac { 1 \ mol \ NaCl}{58.4397693}[/tex]
[tex]\frac {29.22}{58.4397693} \ mol \ NaCl[/tex]
[tex]0.5000019738 \ mol \ NaCl[/tex]
The original measurement of grams has 4 significant figures, so our answer must have the same. For our answer, that is the ten-thousandth place. The 0 to the right of this place (0.5000019738) tells us to leave the 0 in the ten-thousandth place.
[tex]0.5000 \ mol \ NaCl[/tex]
There are approximately 0.5000 moles of sodium chloride in a 29.22 gram sample of sodium chloride.
In a sample of oxygen gas at room temperature, the
average kinetic energy
of all the balls stays constant. Which postulate of kinetic molecular theory
best explains how this is possible?
Answer: The Kinetic Molecular Theory of Matter
Explanation: The answer is: B. Collisions between gas particles are elastic; there is no net gain or loss of kinetic energy.
The Kinetic Molecular Theory of Matter
If you have 8 g of a radioactive element there will be Of the radioactive element left after one half life
Answer:
4g of the radioactive element present
Explanation:
Radioactive elements are atoms that are unstable in normal conditions and are converted in another different atoms.
1 half life express the time that is need to decay the half of the initial amount of the radioactive element.
If initially we have 8g of the radioactive element, after 1 life we will have 8g/2 =
4g of the radioactive element present
Answer the following questions using the chemical equation below:
6CO2 + 6H2O => C6H12O6 + 6O2
3. How many total atoms are on the product side?
4. How many molecules of water are on the reactant side?
write in the chart which molecule is the acid,base, conjugate base,conjugate acid from the equation and watching the H+ movement
1 H2CO3 + H2O--- H3O+ +HCO3-
2 H3PO4 + H2O--- H2PO- +H3O+
3. HCO3- + H2O---H2CO3 +OH-
4 HNO3 +H2O---NO3- +H3O+
Answer:
When H2O acts as a base, it gains one H, which forms its conjugate acid, H30. ... Write the formula for the conjugate base for each of the following acids: a. ... H3PO4(aq) + H2O(l) 7 H2PO4 (aq) + H3O+(aq) ... CO32-(aq) + H2O(1) 2 HCO3 (aq) + OH(aq) ... balanced equation for the reaction of the ammonium ion with water.