1) The percentage of oxygen in dry air is _______
A. 0.1
B. 1.0
C. 21
D. 79
2) The composition of the Earth’s earliest atmosphere was different to that of the present atmosphere. Which of these gases was present in large amounts in the Earth’s earliest atmosphere?
A. Oxygen
B. Carbon dioxide
C. Ammonia
D. Nitrogen
Answer:
1) The percentage of oxygen in dry air is _______
C. 21
2) The composition of the Earth’s earliest atmosphere was different to that of the present atmosphere. Which of these gases was present in large amounts in the Earth’s earliest atmosphere?
B. CARBON DIOXIDE
Hope it helps
have a nice day
Answer: The percentage of oxygen in dry air is . 21
Explanation: Ammonia gases was present in large amounts in the easth7s earliest atmosphere
Hope it will help you
Which is a possible consequence of decreasing air quality resulting from global warming? drying out of fertile lands flooding of low-lying coastal areas melting of glaciers and polar ice caps decrease in population due to health threats The correct answer is decrease in population due to health threats.
Answer: A decrease in population due to health threats is a possible consequence of decreasing air quality resulting from global warming.
Explanation:
When average temperature of Earth keeps on increasing for a longer period of time due to greenhouse gases, increased level of carbon dioxide and other gases etc then it is called global warming.
As humans use oxygen to sustain which is present in the air. So, when there will occur decrease in air quality that results from global warming then it means more illness or diseases will be there.
Hence, people will tend to die more often because of decrease in the air quality their health is getting affected.
Thus, we can conclude that a decrease in population due to health threats is a possible consequence of decreasing air quality resulting from global warming.
Answer:
A decrease in population due to health threats is a possible consequence of decreasing air quality resulting from global warming.
Explanation:
Hope this helps.
Calculate the average atomic mass for element X(please help)
Answer:
Wt Avg At Mass = 39.0229 amu
Explanation:
The Weight Average Atomic Mass in atomic mass units (amu) is the sum of the Weight Average Mass contributions of each isotopic mass. That is,
Wt. Avg. At. Mass (amu) = ∑ Wt. Avg. Contributions of each isotopic mass
Wt. Avg. Contribution = fractional abundance x isotopic mass(amu)
For this problem data:
Isotope %Abundance fractional Isotopic Wt Avg Isotopic
abundance mass(amu) Contribution (amu)
1 9.67% 0.0967 38 3.6746 amu
2 78.68% 0.7868 39 30.6852 amu
3 11.34% 0.1134 40 4.5360 amu
4 0.31% 0.0031 41 0.1271 amu
________________________________________________________
Wt. Avg. Atomic Mass (amu) = ∑ Wt. Avg. Contributions = 39.0229 amu
HELPPPPPPPP i accidentally pressed on c
Answer:
a
Explanation:
I'm not completely sure tho veary sorry if it's wrong
Answer:
the answer is C
Explanation:
as the yeast feeds on sugar and yields the ATP per glucose molecule and Carbon dioxide
ASAP PLEASE ITS FOR MY FINAL!!!!
How would you go about calculating the molarity of the following solution: 19.5 grams of Be(OH)2 is dissolved in enough water to make a 1.5 L solution.
Answer:
0.302M
Explanation:
Molarity, which is the molar concentration of a solution can be calculated as follows:
Molarity = number of moles (n) ÷ volume (V)
According to this question, 19.5 grams of Be(OH)2 is dissolved in enough water to make a 1.5 L solution.
Using mole = mass/molar mass to calculate the number of moles in 19.5g of Be(OH)2
Molar mass of Be(OH)2 = 9 + (16 + 1)2
= 9 + (17)2
= 9 + 34
= 43g/mol
mole = 19.5/43
mole = 0.453moles
Molarity = n/V
Molarity = 0.453/1.5
Molarity = 0.302M
Calculate the molecular weight of a dibasic acid.0.56gm of which is required 250ml of N/20 sodium hydroxide solution for neutralization.
Answer: The molecular weight of the dibasic acid is 89.6 g/mol
Explanation:
Normality is defined as the amount of solute expressed in the number of gram equivalents present per liter of solution. The units of normality are eq/L. The formula used to calculate normality:
[tex]\text{Normality}=\frac{\text{Given mass of solute}\times 1000}{\text{Equivalent mass of solute}\times \text{Volume of solution (mL)}}[/tex] ....(1)
We are given:
Normality of solution = [tex]\frac{1}{20}=0.05N[/tex]
Given mass of solute = 0.56 g
Volume of solution = 250 mL
Putting values in equation 1, we get:
[tex]0.05=\frac{0.56\times 1000}{\text{Equivalent mass of solute}\times 250}\\\\\text{Equivalent mass of solute}=\frac{0.56\times 1000}{0.05\times 250}=44.8g/eq[/tex]
Equivalent weight of an acid is calculated by using the equation:
[tex]\text{Equivalent weight}=\frac{\text{Molar mass}}{\text{Basicity}}[/tex] .....(2)
Equivalent weight of acid = 44.8 g/eq
Basicity of an acid = 2 eq/mol
Putting values in equation 2, we get:
[tex]44.8g/eq=\frac{\text{Molar mass}}{2eq/mol}\\\\\text{Molar mass}=(44.8g/eq\times 2eq/mol)=89.6g/mol[/tex]
Hence, the molecular weight of the dibasic acid is 89.6 g/mol
WHAT IS PHOTOSYNTHESIS??
Answer:
the process by which green plants and some other organisms use sunlight to synthesize nutrients from carbon dioxide and water. Photosynthesis in plants generally involves the green pigment chlorophyll and generates oxygen as a by-product.
Answer:
the process by which green plants and some other organisms use sunlight to synthesize nutrients from carbon dioxide and water. Photosynthesis in plants generally involves the green pigment chlorophyll and generates oxygen as a by-product.
The reaction below shows how the potential energy changes during a phase
change. What does the red arrow show?
Potential Energy
Reaction Progress
A. The change in enthalpy is positive, and the reaction is
endothermic.
B. The change in enthalpy is negative, and the reaction is exothermic.
C. The activation energy is negative, and the reaction is exothermic.
D. The activation energy is positive, and the reaction is endothermic.
Answer:
the red arrow shows that the change in enthalpy is positive
From the energy diagram, it is clear that, the enthalpy of the reaction is positive and it is an endothermic reaction.
What is an endothermic reaction ?An endothermic reaction is a chemical reaction that absorbs heat from its surroundings, resulting in a decrease in temperature of the surroundings. In other words, energy is taken in by the reaction from the environment.
During an endothermic reaction, the reactants absorb energy in the form of heat, light, or electricity to break the bonds between their atoms and form new bonds to create products.
The amount of energy absorbed by the reactants is greater than the energy released by the products. This energy difference is usually expressed as the enthalpy change (∆H) of the reaction, which is positive for endothermic reactions.
Here, the energy of products is higher than that of reactants and hence option A is correct.
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Please a little help in this I will really appreciate it
Answer:
b is your answer...........
What are characteristics of all protests?
Answer:
Explanation:
Una manifestación, protesta o marcha es la exhibición pública de la opinión de un grupo activista (económica, política o social), mediante una congregación en las calles, a menudo en un lugar o una fecha simbólicos y asociados con esa opinión.
What is the percent yield of either if 1.11L(d=0.7134 g/mL) is isolated from the reaction of 1.500L of C2H5OH
Answer:
Percent yield of ether = 83.18%
Explanation:
Equation of the synthesis reaction of ether from ethanol is given as follows :
2 C₂H₅OH -----> C₂H₅OC₂H₅ + H₂0
Density = mass / volume
Therefore mass = density × volume
Density of ether = 0.7134 g/mL; volume of ether produced = 1.11 L = 1110 mL; Molar mass of ether = 74 g/mol
Mass of ether produced = 0.7134 g/mL × 1110 mL = 791.874 g
Density of ethanol = 0.789 g/mL; volume of ethanol = 1.50 L = 1500 mL; molar mass of ethanol = 46 g/mol
Mass of ethanol reacted = 0.789 g/mL × 1500 mL = 1183.5 g
From the equation of reaction, 2 mole of ethanol produces 1 mole of ether
Mass of 2 moles of ethanol = 2 × 46 = 92 g
Therefore, 92 g of ethanol produces 74 g of ether
1183.5 g of ethanol will produce 1183.5 × 74/92 grams of ether = 951.945 g of ether
Percent yield of ether = actual yield/theoretical yield × 100%
Actual yield of ether = 791.874 g; theoretical yield of ether = 951.945 g
Percent yield of ether = (791.874 g × 951.945 g) × 100 %
Percent yield of ether = 83.18%
What kind of reactions are redox reactions
A reaction in which reduction and oxidation take place simultaneously known as a redox reaction.
What pollutants can contribute to acid precipitation and how are these pollutants generated?
Answer:
Acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. These substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.
hope it helps
stay safe healthy and happy...Sulfur dioxide and nitrogen oxides can contribute to acid precipitation.
What are pollutants?A pollutant is a chemical or biological substance which harms water, air, or land quality.
Acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. These substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.
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EN LA MINA DE CHUQUICATAMA SE EXPLOTA DIFERENTES METALES COMO SER EL COBRE , AL ESTAR EN CONTACTO CON EL AIRE DICHO METAL SE LLEGA A OXIDAR FORMANDO DOS CLASES DE OXIDO¿CUALES SON ESTOS DOS OXIDOS?
Answer:
Los dos óxidos que forma el cobre son óxido de cobre (I) y óxido de cobre (II) (Cu₂O y CuO, respectivamente).
Explanation:
El cobre posee dos estados de oxidación más comunes, los cuales son +1 y +2.
En contacto con aire el cobre se puede oxidar para dar lugar al óxido cuproso u óxido de cobre (I):
4Cu + O₂ → 2Cu₂O
Dicha oxidación también puede dar lugar a la formación del óxido cúprico u óxido de cobre (II):
2Cu + O₂ → 2CuO
La formación del óxido cúprico se favorece a temperaturas mayores a la del ambiente (por encima de los 300 °C).
Por lo tanto, los dos óxidos que forma el cobre son óxido de cobre (I) y óxido de cobre (II) (Cu₂O y CuO, respectivamente).
Espero que te sea de utlidad!
In the past mining companies were not made responsible for the clean-up of any of the mine sites. As a result, abandoned mines had a severe impact on the environment in Ontario. Which of these is not a result of these mining practices?
1) Chemical reactions producing sulphuric acid decrease soil and water PH in the area.
2) Acid leaching dissolves metals found in the soil thus allowing them to enter the water system.
3) Heavy metals which are left tailing ponds can dissolve and enter the water system.
4) Old and inefficient mining smokestacks contaminate the soils around abandoned mine sites.
Answer:
Old and inefficient mining smokestacks contaminate the soils around abandoned mine sites.
Explanation:
A smokestack, is a very tall channel commonly used in many instances to release gases produced by combustion processes directly into the air. These high towers are aimed at dispersing the gaseous pollutants over a wider area thereby minimizing their impact.
Old and inefficient smokestack do not contaminate the soil since they are very high towers that discharge gases directly into the atmosphere. Hence they are not part of the sources of soil contamination in abandoned mines.
Help ASAP Iill mark you as brainlister
C. Yes, if each sample contains 6.02 x 10²³ atoms.
help sdfghrthfbfdve aahhhhhhhh
Automobile airbags inflate due to the formation of nitrogen gas from the chemical reaction 2NaN3(s)—> 3N2(g)+2Na(s) Identify the number of each atom in the reactants and products for this balance reaction.
¿Qué características distinguen a los coloides de otras mezclas?
Select the correct text in the passage.
Explanation:
Oceans can influence weather and climate. For example, cities located near large water bodies like oceans tend not to have extreme climates
If 250 grams of water is to be heated from 24.0°C to 100.0°C to make a cup of tea, how much
heat must be added? The specific heat of water is 4.18 J/g∙C
Answer:
[tex]\boxed {\boxed {\sf 79,420 \ J}}[/tex]
Explanation:
We are given the mass, a change in temperature, and the specific heat of water. We should use the following formula to solve this problem.
[tex]q=mc\Delta T[/tex]
In this formula, m is the mass, c is the specific heat, and ΔT is the change in temperature.
We know there are 250 grams of water and the specific heat of water is 4.18 J/g · °C.
We are given two temperature, so have to find the change in temperature. This is the difference between the initial temperature and final temperature. The water is heated from 24 °C to 100 °C. Therefore, the initial is 24 and the final is 100.
[tex]\bullet \ \Delta T= T_{final} - T_{initial} \\\bullet \ \Delta T=100 \textdegree C - 24 \textdegree C\\\bullet \Delta T= 76 \textdegree C[/tex]
Now we know all three of the variables and we can substitute them into the formula.
[tex]\bullet \ m= 250 \ g\\ \bullet \ c=4.18 \ J/g \textdegree C \\ \bullet \ \Delta T= 76 \textdegree C[/tex]
[tex]q= (250 \ g)( 4.18 \ J/g * \textdegree C)( 76 \textdegree C)[/tex]
Multiply the first two numbers together. The units of grams will cancel.
[tex]q= (1045 \ J/\textdegree C)(76 \textdegree C)[/tex]
Multiply again. This time, the units of degrees Celsius cancel.
[tex]q= 79420 \ J[/tex]
79, 420 Joules of heat must be added.
if you have a pop quiz and you get nervous is that unconditioned response? if yes why? if not what kind of response is it
Give a real-world example of an energy transformation that uses two of the following forms of energy: chemical, mechanical, nuclear, gravitational, radiant, electrical, thermal (heat), and/or sound.
Answer:
Nuclear energy gets converted into heat energy during a detonation and is also used in nuclear power plants where the heat energy form the nuclear energy gets converted into mechanical energy by converting water into steam, rotating the turbines and converting that into electrical energy
Explanation:
Or heat engines, such as the internal combustion engine used in cars, or the steam engine. (Heat - Mechanical energy)
Can someone please do a True or false for these PLEASE
Answer:
true
false
false
true
false
true
true
false
false
true
true
Oxygen is a diatomic element.why give reason.
Answer:
Diatomic molecules contain two atoms that are chemically bonded. If the two atoms are identical, as in, for example, the oxygen molecule (O2), they compose a homonuclear diatomic molecule, while if the atoms are different, as in the carbon monoxide molecule (CO), they make up…
Explanation:
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Options ^
QUESTION:
Which of the following choices will an atom of sodium (Na) be most likely to bond with?
Answer:
A. 2 chlorine (Cl) atoms
Explanation:
2 chlorine atoms means that chlorine is a gas.
Sodium (Na) reacts with 2 chlorine atoms according to the equation below;
Na(s) + Cl2(g) => NaCl2
Answer:
fluorine is what its looking for
Explanation:
Iron reacts with copper (I) sulfate to produce copper and iron (II) sulfate. If 4.32x10^25
particles of copper (I) sulfate react, how many moles of copper will be produced?
Fe + Cu2504 --> FeSO4 + 2Cu
Answer: 143.48 moles of copper will be produced.
Explanation:
We are given:
Number of particles of copper (I) sulfate = [tex]4.32\times 10^{25}[/tex]
According to the mole concept:
[tex]6.022\times 10^{23}[/tex] number of particles is contained in 1 mole of a compound
So, [tex]4.32\times 10^{25}[/tex] number of particles will be contained in = [tex]\frac{1}{6.022\times 10^{23}}\times 4.32\times 10^{25}=71.74mol[/tex] of copper (I) sulfate
The given chemical equation follows:
[tex]Fe+Cu_2SO_4\rightarrow FeSO_4+2Cu[/tex]
By the stoichiometry of the reaction:
If 1 mole of copper (I) sulfate produces 2 moles of Cu
So, 71.74 moles of copper (I) sulfate will produce = [tex]\frac{2}{1}\times 71.74=143.48mol[/tex] of Cu
Hence, 143.48 moles of copper will be produced.
If you refuse a legal chemical test issued by a law enforcement officer, the Division of Motor Vehicles is required to:
Answer: Revoke the driver's license for at least 12 months
Explanation:
Chemical tests are used in order to measure the amount of drugs or alcohol that is in the body of a person when the person was arrested. To do this, samples of the urine or blood of the person can be taken and the result will be used to know if the person was driving under the influence of alcohol or not.
If the person refuse a legal chemical test issued by a law enforcement officer, the Division of Motor Vehicles is required to revoke the the driver's license of the person for at least 12 months.
The charge on a charged sphere is concentrated at (or on) its ________.
Central Core
Interior
Surface
I ANSWERED IT BUT SOMEONE SYAYS ITS COPY SO WHAT COULD I DO ;(
Answer:
The charge on a charged sphere is concentrated at (or on) its central core .hope it is helpful to you
solve this question please! it have 3 options which one of them is correct option
Answer:
I think option two (2) is the correct answer
