Answer:
The first step in the Scientific Method is to make objective observations. These observations are based on specific events that have already happened and can be verified by others as true or false. Step 2. Form a hypothesis.
Answer:
False
Explanation:
The first step of the scientific method is to make an observation.
2. School bus accidents are very rare, possibly because they are so easy to see.
School buses have been around since 1915, but the official color of bright
yellow wasn't used until 1939. Would grey school buses get in more accidents?
Help plz!!!
Answer:
Grey school buses would likely get in more accidents because other drivers are expecting a yellow bus to make frequent stops and the lights and stop sign are noticeable on a brighter color.
Explanation:
yellow buses are easier to see in fog than a grey bus
The boiling point of water is 100ºC. The boiling point of acetone is 56ºC. Which statement about distilling a mixture of acetone and water is correct?
Acetone remains in the original container.
Water will vaporize from the mixture before acetone.
Acetone is captured and cooled.
Water is collected as it leaves the mixture.
Answer:
Acetone is captured and cooled.
Explanation:
The boiling point of acetone is lower than that of water, so it will vaporise before water. Then acetone will be captured and cooled to separate it from its mixture with water.
The statement which is correct about distilling a mixture of acetone and water is as follows:
Acetone is captured and cooled.Thus, the correct option is C.
What is Distillation?Distillation may be defined as a procedure that generally involves the conversion of a liquid into a vapor that is eventually condensed back to liquid form. With the help of this process, the separation of components or substances from a liquid mixture by using selective boiling and condensation occurs.
Acetone has the lowest boiling point as compared to water. So, it boils faster than that water and vaporizes before water. After the termination of this process, the acetone will be predominantly captured and cooled to separate it from its mixture with water.
Therefore, the correct option for this question is C.
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the first attempt to classify the elements was made by newlands true or false
Answer:
True. An English scientist by the name of John Newlands tried to classify the elements in a unique manner. He first started by arranging all the elements in a ascending order according to their atomic weights.
Study the scenario. The particles in a system are moving around very slowly. A few minutes later, the particles are moving, on average, much faster. How does this change in motion affect the temperature of the system? the temperature increase since the average kinetic energy of the particles increases the temperature remains the same since temperature is a measure of potential energy of a system, not the movement of its particles it is not possible to tell since temperature is a result of the fastest moving particles in a system, not the average the temperature decreases since the average kinetic energy of the particles increases
Answer:
The average kinetic energy of the system has increased as a result of the temperature increasing.
Explanation:
Assuming this is a gas based on the framing.
The molecules of a gas span a distribution of speeds, and the average kinetic energy of the molecules is directly proportional to the absolute temperature of the sample. KEavg is proportional to T.
This can be further studied until the Kinetic-Molecular Theory.
what are the 2 main methods of combination of elements??
Answer:
to make them react to each other to form a compound
Explanation:
mark me as brainliest pls
Answer:
An element is a material that consists of a single type of atom. Each atom type contains the same number of protons. Chemical bonds link elements together to form more complex molecules called compounds. A compound consists of two or more types of elements held together by covalent or ionic bonds.
Silica (also known as silicon dioxide) reacts with hydrofluoric acid to produce silicon tetrafluoride and water vapor.
a) Write the balanced chemical equation for the reaction
b) 12.5 g of silicon dioxide is reacted with a 24.6 g of hydrofluoric acid. What is the theoretical yield of water vapor?
c) If the actual yield of water vapor is 2.50 g, what is the percentage yield of the reaction?
The problem is solved by balancing the reaction equation as shown below. The stoichiometry of the reaction is now applied in solving the question.
The balanced reaction equation is:
SiO2 + 6HF → H2[SiF6] + 2H2O
Using stoichiometry
The amount of silicon dioxide reacted = 12.5 g/60.08 g/mol = 0.21 mole
1 mole SiO2 yields 2 moles of H2O
0.21 mole of SiO2 yields 0.21 * 2/1 = 0.42 moles of H2O
The amount of HF reacted = 24.6 g/20.01 g/mol = 1.23 moles of HF
6 moles of HF yield 2 mole of H2O
1.23 moles of HF yields 2 * 1.23/6 = 0.41 moles of H2O
Hence HF is the limiting reactant.
Theoretical yield of H2O = 0.41 moles of H2O * 18 g/mol = 7.38 g
The percentage yield of the water is = actual yield/theoretical yield * 100
Hence;
% yield = 2.50 g/7.38 g * 100 = 33.9%
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please Help!! And answer ASAP!!! Give two examples of compounds that form extended structures instead of molecules. Using a complete
sentence.
Answer:
A structure whose sub-units occur in a constant ratio and are arranged in a repeating pattern; the sub-unit can be individual atoms or a molecule.
Heterometallic systems Which employ multiple building units to produce extended structures.
And
Design and assessment of extended structures often require the generation of spatially variable earthquake motions to be used as multiple-support inputs.
Explanation:
Such As A Polymer For Instance.
A type of extended structure that is made of many smaller, repeating sub-units in a chain; Although, The repeating sub-unit is a unique molecule. I Hope That This Answer Helps.
In an electrochemical cell, equilibrium is the point at which:
A. None of these
B. both electrodes have an equal number of electrons.
C. ion concentrations are no longer changing and the voltage is 0.
D. Equilibrium cannot be reached in a voltaic cell because electrons only flow in one direction.
Answer:
C. ion concentrations are no longer changing and the voltage is 0.
Explanation:
Electrochemical cells are a device that generates current from redox reactions. In the cell, the equilibrium is reached when the voltage drops to 0. Thus, option C is correct.
What is an electrochemical cell?An electrochemical cell is a voltaic device that uses chemical energy to generate electrical energy and vice versa. It is of two types electrolytic and galvanic cells depending on the energy it produces.
The electrochemical cell comprises two electrodes namely an anode and cathode, a salt bridge or the porous barrier, and an external connection.
The connection shows the voltage that indicates the equilibrium. When the current flow stops and the voltage reaches zero, the electrochemical cell is said to be in equilibrium.
Therefore, no change in the ionic concentrations and zero voltage indicates equilibrium.
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describe any four factors that bring out a chemical change.
Answer:
Physical state of reactants
Temperature
Concentration of reactants
Presence of a catalyst
Explanation:
The larger the surface area of a reactant, the faster the rate of the reaction. If the reactant is in powdered form, the reaction takes place faster than when the reactant is in solid or block form. This is due to the fact that the latter has larger surface area
Increase in temperature causes reactant molecules to gain kinetic energy thus increasing the rate if reaction
What is a base?
A. A substance that increases the concentration of oxygen in
solution
B. A substance that increases the concentration of OH ions in
solution
C. A substance that increases the concentration of H+ ions when dissolved
D. A substance that contributes chloride ions to the solution
Answer:
A base releases OH~ in a solution, so the answer is B
The volume of a gas was 48 mL when the temperature was 159.6 ºC. If the temperature was initially 4.9 ºC, and there was no change in the pressure, what was the initial volume of the gas?
According to Charles law
[tex]\boxed{\sf \dfrac{V_1}{T_1}=\dfrac{V_2}{T_2}}[/tex]
[tex]\\ \sf\longmapsto \dfrac{48}{159.6}=\dfrac{V_2}{4.9}[/tex]
[tex]\\ \sf\longmapsto V_2=\dfrac{48\times 4.9}{159.6}[/tex]
[tex]\\ \sf\longmapsto V_2=\dfrac{235.2}{159.6}[/tex]
[tex]\\ \sf\longmapsto V_2=1.4mL[/tex]
prepare a dialogue between two friends about development of society .
Answer:
Pls pls pls mark brainliest
The law of conservation of energy states that A: energy is always created and destroyed B: energy cannot be created or destroyed C: energy is unable to change forms D: energy should be saved as often as possible
Answer:
B
Explanation:
This is the First Law of Thermodynamics which states that energy cannot be created or destroyed.
Answer: Freezing point depression
Explanation:
freezing point depression is a phenomenon that describes why adding a solute or solvent results in the lowering of the freezing point of the solvent
hurry
A solution:
A. is a mixture that is made when a solid dissolves and combines with a liquid.
B. is the amount of a substance that will combine with another substance before they begin to chemically combine.
C. is the amount of a substance that will dissolve in 1 dm3 of water at 25 C .
D. is two or more substances that are combined together but not chemically joined.
Reset Selection
Answer:
b is the correct answer ok
A solution is made up of solute and solvent. It is an addition of two or more substances to each other that combines physically and chemically. Thus, option B is correct.
What is a solution?A solution is the mixture of solutes that can be more than one in a solvent that has the same composition all over (homogenous). A solution comprises two main elements called a solute and a solvent.
A solute is the part of the solution that has been added to the solvent for desolvation. On the other hand, the solvent is the substance that dissolves the solute in them to make a solution.
The homogenous mixture or the solution can be created by mixing salt and water, sugar and water, mercury in amalgamated zinc, coffee, vinegar, etc.
Therefore, option B. a solution is the addition of the substances that combine physically.
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Modern periodic table is based upon atomic number. Explain what does the modern periodic table states about the atomic numbers ?
Answer:
Explanation:Elements of the periodic table are arranged in order of increasing atomic number. The periodic law states “When elements are arranged in order of increasing atomic number, there is a periodic repetition of their chemical and physical properties.”
22.5 ml of a 0.200 m HBr solution was added to a 50.00 ml sample of 0.250 m sodium benzoate (NaC7H5O2). Calculate the pH. Benzoic acid has a Ka 6.30 x 10-5.
In this problem, we need to find the pH of a buffer (pH = 4.45) that is produced by the reaction of strong acids as HBr that reacts with weak bases as NaC₇H₅O₂ producing its weak acid and a salt, as follows:
HBr + NaC₇H₅O₂ → HC₇H₅O₂ + NaBr
If in the reaction, the limiting reactant is the strong acid, we will produce a buffer (The aqueous mixture of a weak acid and its strong base).
Using Henderson-Hasselbalch equation, we can find the pH of this buffer:
[tex]pH = pKa + log \frac{[NaC_7H_5O_2]}{[HC_7H_5O_2]}[/tex]
Where:
pKa is -log Ka = 4.20
[] could be taken as the moles of each species
After the reaction, the moles of HBr = Moles of HC₇H₅O₂ and the remaining moles of NaC₇H₅O₂ = Initial moles of NaC₇H₅O₂ - Moles of HBr.
Moles HBr:
22.5mL = 0.0225L * (0.200mol/L) = 4.5x10⁻³ moles HBr
Moles NaC₇H₅O₂:
50.0mL = 0.0500L * (0.250mol/L) = 0.0125 moles NaC₇H₅O₂
That means the moles after the reaction of the species of the buffer are:
Moles HC₇H₅O₂ = Moles HBr = 4.5x10⁻³ moles
Moles NaC₇H₅O₂ = 0.0125 moles - 4.5x10⁻³ moles = 8.0x10⁻³ moles
Replacing in H-H equation:
[tex]pH = 4.20+ log \frac{[8.0x10^{-3}]}{[4.5x10^{-3}]}[/tex]
pH = 4.45
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How many neutrons are present in 4.4 gram of Co2
Explanation:
hope it will help you Mark me as a brilliant
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what compound has a molar mass of 37.11 g/mol
Answer:
Explanation:
The closest I can come to this is
Li C2H5 which would really be weird, but it comes to nearly 37.11. Everything depends on the periodic table you are using.
C2 = 2 * 12.011 = 24.022
H5 = 5 * 1.008 = 5.040
Li = 1 * 6.94 6.94
Total 36.002
Pesticides and fertilizers are a major cause of
O air pollution
O acid rain
o the greenhouse effect
O groundwater pollution
Answer:
it means air pollution Environment. The chemicals and nutrients found in fertilizers, while beneficial for agricultural crops, can be lethal in high doses for fish, birds and other wildlife. Pesticides, designed to kill pests chemically, are also dangerous when leached into soil or groundwater supplies.
Energy in the amount of 420 J is added to a 35 g sample of water at a temperature of 10°C. What is the final temperature of the water?
The final temperature of the water, T2 = 38.57°C
Temperature can be defined as a measure of the degree of hotness or coldness of a physical object (body). Thus, it is measured with a thermometer and its units are degree Celsius (°C), Fahrenheit (°F) and Kelvin (°K).
A calorie refers to the amount of heat required to raise the temperature of a gram of water by one (1) degree Celsius (1°C).
Given the following data:
Quantity of energy = 420JMass = 35 gramsInitial temperature, T1 = 10°CThe specific heat capacity of water is 4.2 J/g°C.
To find the final temperature of the water (T2):
Mathematically, the quantity of energy (heat capacity) is given by the formula;
[tex]Q = mcdt[/tex]
Where;
Q represents the heat capacity or quantity of heat.M represents the mass of an object.C represents the specific heat capacity of water.dt represents the change in temperature.Substituting the values into the formula, we have;
[tex]420 = 3.5 \; * \; 4.2 \; * \; dt[/tex]
[tex]420 = 14.7 \; * \; dt\\\\dt = \frac{420}{14.7}[/tex]
Change in temperature, dt = 28.57°C
Next, we would solve for the final temperature by using this formula;
[tex]dt = T2 - T1[/tex]
[tex]28.57 = T_{2} - 10\\\\T_{2} = 28.57 \; + \; 10\\\\T_{2} = 38.57[/tex]
Final temperature, T2 = 38.57°C
Therefore, the final temperature of the water, T2 is equal to 38.57°C
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Which of the following properties would helium have?
A. Closely packed and structured particles
B. Fills entire container
C. Definite volume
D. Definite shape
Reset Selection
Answer:
B
Explanation:
It is a gas and therefore according to particle model of matter it has large spaces between them and does not have a definite shape
Among the following properties, Helium would fills entire container. Hence Option (B) is correct.
What is States of Matter ?
A “state of matter” is a way to describe the behaviour of atoms and molecules in a substance.
There are three common states of matter: Solids – relatively rigid, definite volume and shape. In a solid, the atoms and molecules are attached to each other. They vibrate in place but don't move around.
Helium is a gas in nature and thus fills entire container.
Therefore, Among the following properties, Helium would fills entire container. Hence Option (B) is correct.
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is a corroding metal a physical or chemical change?
Answer:
Corrosian is a chemical change
Explanation:
Which of the following is the best definition of a physical property?
A. Tearing paper in half.
B. Something that can be observed or measured while changing the identity of the substance.
C. The ability of something to undergo a change or reaction.
D. Something that can be observed or measured without changing the identity of the substance.
Answer:
D.Something that can be observed or measured without changing the identity of the substance.
Cellular respiration occur within ______ of a cell.
Answer:
The mitochondria
Explanation:
Its where cellular respiration occurs
What types of mixtures are these?
Explanation:
Homogeneous Mixture:-
A cup of tea and sugarFood coloring dissolved in waterHeterogeneous Mixture:-
Peanuts and almonds mixed together in a bowlA bucket full of sand and gravelPLEASE HELP URGENT!!!! 20 POINTS!!!!!
Identify the most common graph types, and explain what each is used for.
Explanation:
Bar Graph.Segmented Bar Graph.Column Graph. Whiskers Graph (also called a Box Plot)Frequency Graph (Frequency Table)Cumulative Frequency Table.Frequency Polygon.Histogram.BAR GRAPH
The bar graph is used to compare the items between different groups over time, bar graphs are used to measure the changes over a period of time, when the changes are larger, a bar graph is the best option to represent the data.
SEGMENTED BAR GRAPH
A segmented bar graph is used to compare two categories within a data set, the whole bar represents all the data within one category. Then, each bar is separated into parts (segments) that show the percentage of each part in the second category.
COLUMN GRAPH
A column graph summarizes categorical data by presenting parallel vertical bars with a height (and hence area) proportionate to specific quantities of data for each category, this type of graph can be useful in comparing two or more distributions of nominal- or ordinal-level data.
WHISKERS GRAPH
A box and whisker plot is a way of summarizing
a set of data measured on an interval scale, it is often used in explanatory data analysis, this type of graph is used to show the shape of the distribution, its central value, and its variability.
FREQUENCY GRAPH
Frequency tables, pie charts, and bar charts can be used to display the distribution of a single categorical variable,these displays show all possible values of the variable along with either the frequency (count) or relative frequency (percentage).
CUMULATIVE FREQUENCY GRAPH
Cumulative frequency is used to determine the number of observations that lie above (or below) a particular value in a data set, the cumulative frequency is calculated by adding each frequency from a frequency distribution table to the sum of its predecessors.
FREQUENCY POLYGON
A frequency polygon is a graphical form of representation of data, it is used to depict the shape of the data and to depict trends, It is usually drawn with the help of a histogram but can be drawn without it as well. Frequency polygons are a graphical device for understanding the shapes of distributions.
HISTOGRAM
A histogram is used to summarize discrete or continuous data, in other words, it provides a visual interpretation of numerical data by showing the number of data points that fall within a specified range of values (called “bins”). It is similar to a vertical bar graph.
How does a balanced chemical equation represent the conservation of
matter in a chemical reaction?
1. There are more atoms in the reactants than in the products.
2. The type of matter in the products is different from the type of matter in
the reactants.
3. The number of atoms of each element in the reactants equals the number
of atoms of each element in the products.
4. There are fewer atoms in the reactants than in the products
Answer:
The correct answer would be 3. The number of atoms of each element in the reactants equals the number of atoms of each element in the products.
Explanation:
The law of conservation of matter states that energy cannot be created or destroyed, only transfered. Thus, option 3 is correct.
How IS energy related to the change of state represented
by the model?
Atoms gain energy as a solid changes to a gas.
Atoms gain energy as a liquid changes to a gas.
Atoms lose energy as a solid changes to a gas.
Atoms lose energy as a liquid changes to a gas.
Answer:
Gain energy as a liquid changes to a gas
Explanation:
get further apart= more kinetic energy
liquid at beginning as not uniform but quite close together and takes shape of container
The answer is...Liquid into gas.
My Explanation:
Stated in the model, The atoms aren't that active but can still slider past each other; meaning, this is a liquid. As it shifts into a gas, which is when atoms pick up energy and move around more freely/actively, the definition of the following is "Vaporization".
So the answer is: B, or in other words, "Atoms gain energy as a liquid turns into a gas.
how does activation energy affect the process of a reaction
Answer:
The activation energy increases how quickly the reaction will progress.
Explanation:
The activation energy of a chemical reaction is intimately linked to its rate. Particularly, the greater the activation energy, the slower the chemical reaction will be. The reason is: molecules can only finish the reaction as soon as they have reached the peak of the activation energy barrier. Many reactions possess such huge activation energies that they practically don't advance at all without an input of energy.
The activation energy of a particular reaction determines the rate at which it will proceed. The higher the activation energy, the slower the chemical reaction will be.
