Answer:
The answer is "-50.424° C".
Explanation:
Given:
Time = 1 hour
TB=?
Formula:
[tex]TB= \frac{-T\times P}{m \times c_i}[/tex]
time (T) = 1 hour
= 3600 second
[tex]t=(3600 -t_2)[/tex]
Calculating T_B:
[tex]\to T_B= \frac{-(3600 - t_2) 36.6}{0.250 \times 2090}\\[/tex]
[tex]= \frac{-(3600 - 2880) 36.6}{522.6}\\\\= \frac{-(720) 36.6}{522.6}\\\\= \frac{-720 \times 36.6}{522.6}\\\\= \frac{-26352}{522.6}\\\\= -50.424 ^{\circ} C[/tex]
Which of the following hypotheses is testable by using the scientific method?
a) all man are mortal
b) the best color is blue
c) no life exists on other planets
d) all swans are white
e) swimming if fun
Answer:
d
Explanation:
The only hypothesis that is testable using the scientific method would be that all swans are white.
The scientific method involves a series of steps through which scientists are able to arrive at a conclusion about the natural world. The steps include observation, drawing up falsifiable hypotheses from observations, testing the hypotheses using experiments, and then arriving at conclusions based on the data gathered from the experiment.
There is no way to test the mortality of all men as this will require harming humans in order to prove their mortality. The best color is also subjective as individuals have their preference when it comes to color. There is no way to prove the hypothesis that no life exists on other planets as this will require visiting other planets, a gesture that is practically impossible. That swimming is fun can also be subjective. Not everyone finds swimming interesting.
The hypothesis that all swans are white can be tested by sampling the population of swans in different areas and recording their colors objectively.
Hence, the correct option is d.
The hypothesis 'all swans are white' is testable by using the scientific method (Option d).
The scientific method is a series of sequential steps by which it is possible to find an explanation to scientific questions.The hypotheses are plausible explanations used by scientists to answer questions on the natural world.A hypothesis must be testable which means it is positive to make observations that agree or disagree with such explanation.In conclusion, the hypothesis 'all swans are white' is testable by using the scientific method (Option d).
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Peripherals are used to?
Answer:
Peripheral device, also known as peripheral, computer peripheral, input-output device, or input/output device, any of various devices (including sensors) used to enter information and instructions into a computer for storage or processing and to deliver the processed data to a human operator or, in some cases.
Explanation:
Hope it helps
Answer: Input and output data
Explanation:
Plato!!!!!!!!!
Which has the greatest mass?a. one atom of carbon, b. one atom of hydrogenc. one atom of lithium
Answer:
one atom of carbon
Explanation:
The relative atomic mass of elements can be used to determine their relative masses. If we look at all the options, we will notice that carbon has a relative atomic mass of 12, hydrogen has a relative atomic mass of 1 and lithium has a relative atomic mass of 7
We can now see that carbon has the greatest relative atomic mass among the options provided in the question.
3. How many significant figures are in the number 805000? *
Answer:
3
Explanation:
Three significant figures
Students in a science class placed ice cubes in a cup. They were studying variables that affected how long it takes the ice to melt. Select the variable that
would most likely NOT affect the time it takes the ice to melt.
O Size of cup
O Size of ice cube
O Number of students
O Temperature of the room
Answer:
Number of students-this has nothing to do with the question, its called a distractor.
The variable that would most likely not affect the time it takes the ice to melt is the Number of students. The correct option is C.
What are the variables in the experiments?Variables are the different substances or objects that participate in the experiment directly or indirectly. They are substances that together form the experiment. These variables impact the result of the experiment.
There are two types of variables. They are Dependent and independent variables. Dependent variables can be controlled in the experiment, but independent variables can't be controlled.
Students are performing the experiment, so they cannot be the variables because their presence or absence would be to impact the experiment.
Thus, the correct option is C. Number of students.
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Predict whether the following reactions are spontaneous.
1. Pd(aq)2+H2g--------->Pd(s)+2H(aq+) Pd(aq2+) +2e- ----------> Pd(s)
E° 0.987 v
2. Sn(aq4+)+H2(g)--------->Sn(aq2+)+2H+ Sn(aq4+)+2e--------->Sn(aq)2+
E°0.154V
3. Ni(aq2+)+H2(g)--------->Ni(s)+2H(aq+) Ni(aq2+) +2e---------->Ni(s)
E° -0.250 V
4. Cd(aq2+)+H2(g--------> Cds)+2H(aq)+ Cd(aq)2 + +2e -------->
Cd(s) E°-0.403 v
From your answers, decide which of the above metals could be reduced by hydrogen
Answer:
1. spontaneous
2. spontaneous
3. Not Spontaneous
4. Not Spontaneous
Palladium and Sn^4+ can be reduced by hydrogen.
Explanation:
If we look at the electrochemical systems represented above, we will notice that in the first two cells, the metal should be reduced looking at the positive electrode potential of the process. This means that hydrogen can reduce the both metals. Electrons flow from the H2(g)/H^+(aq) half cell to the metal/metal ion half cell.
Similarly, when the standard electrode potential is negative, electrons flow from the metal/metal ion electrode to the hydrogen electrode.
Based on the reaction equations, a process is spontaneous if it gives a positive E°cell hence the answers above.
Determine the pH of the resulting solution if 25 mL of 0.400 M strychnine (C21H22N2O2) is added to 50 mL of 0.200 M HCl? Assume that the volumes of the solutions are additive. For strychnine at the temperature of the experiment, Kb = 1.8 × 10-6.
Answer:
pH = 4.56
Explanation:
The strychnine reacts with HCl as follows:
C₂₁H₂₂N₂O₂ + HCl ⇄ C₂₁H₂₂N₂O₂H⁺ + Cl⁻
For strychnine buffer:
pOH = 5.74 + log [C₂₁H₂₂N₂O₂H⁺] / [C₂₁H₂₂N₂O₂]
Initial moles of C₂₁H₂₂N₂O₂ are:
0.025L * (0.400 mol / L) = 0.01 moles C₂₁H₂₂N₂O₂
And of HCl are:
0.05L * (0.200 mol / L) = 0.01 moles HCl
That means after the reaction, you will have just 0.01 moles of C₂₁H₂₂N₂O₂H⁺ in 50mL + 25mL = 0.075L. And molarity is:
[C₂₁H₂₂N₂O₂H⁺] = 0.01 mol / 0.075L = 0.1333M
This conjugate acid, is in equilibrium with water as follows:
C₂₁H₂₂N₂O₂H⁺(aq) + H₂O(l) ⇄ C₂₁H₂₂N₂O₂ + H₃O⁺
Where Ka = Kw / Kb = 1x10⁻¹⁴ / 1.8x10⁻⁶ = 5.556x10⁻⁹
Ka is defined as:
Ka = 5.556x10⁻⁹ = [C₂₁H₂₂N₂O₂] [H₃O⁺] / [C₂₁H₂₂N₂O₂H⁺]
In equilibrium, concentrations are:
C₂₁H₂₂N₂O₂ = X
H₃O⁺ = X
C₂₁H₂₂N₂O₂H⁺ = 0.1333M - X
Replacing in Ka expression:
5.556x10⁻⁹ = [X] [X] / [0.1333M - X]
7.39x10⁻¹⁰ - 5.556x10⁻⁹X = X²
7.39x10⁻¹⁰ - 5.556x10⁻⁹X - X² = 0
Solving for X:
X = - 2.72x10⁻⁵M → False solution. There is no negative concentrations
X = 2.72x10⁻⁵M → Right solution.
As H₃O⁺ = X
H₃O⁺ = 2.72x10⁻⁵M
And pH = -log H₃O⁺
pH = 4.56Which of the following is included in nuclide symbols, but is not strictly necessary for the identification of the nuclide?
a. mass number
b. atomic number
c. isotope number
d. none of the above
Answer:
c. isotope number
Explanation:
Mass Number is the sum total of mass of protons and neutrons present in the nucleus of an atom. Generally they are being used in distinguishing isotopes. E.g Carbon - 12, Carbon - 13
Atomic Number is the number of protons. Every single element has it's unique atomic number and can be used in identification purpose. E.g Carbon - 6, Hydrogen - 1.
The correct option is option C. This is the symbol that is not necessary for the identification of a nuclide.
Answer: B, atomic number
Acetyl chloride undergoes nucleophilic substitution at a faster rate than methyl acetate because:_________
A) the ester is more sterically hindered than the acid chloride.
B) the acid chloride is more sterically hindered than the ester.
C) the methoxide is a better leaving group than chloride.
D) esters hydrolyze faster than acid chlorides.
E) chloride is a better leaving group than methoxide.
The liquid 2-chloro-2,3-dimethylbutane has a density of 0.878 g/mL at 20.0°C. If a 138 gram sample of this compound is needed, what volume of the liquid at 20.0°C must be provided? volume= mL
Answer:
157.2 mL
Explanation:
The following data were obtained from the question:
Density (D) of liquid = 0.878 g/mL
Mass (m) of liquid = 138 g
Volume (V) of liquid =.?
Density of a substance is simply defined as the mass of the substance per unit volume of the substance. Mathematically, it is expressed as:
Density (D) = mass /volume
D = m/V
With the above formula, we can obtain the volume of the liquid as follow:
Density (D) of liquid = 0.878 g/mL
Mass (m) of liquid = 138 g
Volume (V) of liquid =.?
D = m/V
0.878 = 138/V
Cross multiply
0.878 × V = 138
Divide both side by 0.878
V = 138/0.878
V = 157.2 mL
Therefore, 157.2 mL of the liquid must be provided.
the distance between atomes is sometimes given in picometers,where 1pm is equivalent to 1×10^12m if the distance between the carbon atomes in diamond is 2.81×10^8,what is the distance in picometers?
Answer:
Distance between the carbon atom = 491 pm
Explanation:
Given:
1 pm = 1 × 10⁻¹² m
Distance between the carbon atom = 2.81 × 10⁻⁸ cm
Find:
Distance in picometers
Computation:
Distance between the carbon atom = 2.81 × 10⁻⁸ cm = 491 X 10⁻¹² m
Distance between the carbon atom = 491 pm
Dinitrogen tetroxide and hydrazine (N2H4) undergo a redox reaction in which nitrogen and water are formed as products. What mass of nitrogen could be produced when 50.0 g of dinitrogen tetroxide and 45.0 g of hydrazine are combined?
Answer:
The mass of nitrogen molecule [tex]N_2[/tex] = 45.65 g
Explanation:
The equation for the redox reaction can be represented as follows:
[tex]\mathtt{2N_2H_4 +N_2O_4 \ \to \ 3N_2 + 4H_2O}[/tex]
We know that:
numbers of moles = mass/molar mass
For [tex]\mathtt{N_2O_4}[/tex] :
number of moles = 50g/92 g/mol
number of moles = 0.5435 mol
For [tex]\mathtt{N_2H_4}[/tex] :
number of moles = 45 g/ 32 g/mol
number of moles = 1.40625 mol
From the above equation;
number of moles of [tex]\mathtt{N_2O_4}[/tex] needed = 1/2 moles of [tex]\mathtt{N_2H_4}[/tex] = 1/2 × 1.40625 mol
= 0.703125 mol
The amount of [tex]\mathtt{N_2O_4}[/tex] present = 0.5435 moles which is less than the needed. As such [tex]\mathtt{N_2O_4}[/tex] is the limiting reagent
The number of moles of nitrogen molecule [tex]N_2[/tex] produced = 3 × ([tex]\mathtt{N_2O_4}[/tex])
= 3 × 0.5435
= 1.6305 mol
The mass of nitrogen molecule [tex]N_2[/tex] = number of moles of [tex]N_2[/tex] × molar mass of [tex]N_2[/tex]
The mass of nitrogen molecule [tex]N_2[/tex] = 1.6305 mol × 28 g/mol
The mass of nitrogen molecule [tex]N_2[/tex] = 45.654 g
The mass of nitrogen molecule [tex]N_2[/tex] = 45.65 g
The value of the equilibrium constant for a reaction is 2.65 x 10-6 at 35° Calculate the value of LaTeX: \DeltaΔG°rxn.
Answer:
The answer is "33.95 [tex]\bold{ \frac{kj}{mol}}\\[/tex]".
Explanation:
Formula:
[tex]\bigtriangleup G_0= -R \times T l_n \times K_{eq}\\[/tex]
where
[tex]K_{eq} = \text{equilibrium constant}\\[/tex]
Given value:
[tex]T =35^{\circ} C\\[/tex]
convert temperature celsius (°C) to Kelvin (K):
[tex]= (273+45) \ kelvin \\\\= 318 \ Kelvin \\\\= 318 \ K[/tex]
[tex]R = 8.314 \ \ \frac{J}{ mol \cdot K}[/tex]
[tex]\bigtriangleup G_0= -(8.314 ) \times 31.8 \times l_n (2.65\times 10^{-6})\\[/tex]
[tex]=-(8.314 ) \times 31.8T l_n \times (2.65\times 10^{-6})\\\\[/tex]
After solving the value it will give:
= 33.95 [tex]\bold{ \frac{kj}{mol}}\\[/tex]
what is the color of dilute hydrochloric acid when we use the universal indicator ? only given that it is corrosive
Answer:
dark red
Explanation:
because dilute hcl is acid
dark red is the correct answer.
HCl(aq) + NaOH(aq) ––––> NaCl(aq) + H2O(l) What volume of 0.631 M HCl is required to react with 15.8 mL of 0.321 M NaOH?
Answer:
The correct answer is 8.04 mL
Explanation:
Given the neutralization reaction:
HCl(aq) + NaOH(aq) ––––> NaCl(aq) + H₂O(l)
1 mol of HCl reacts with 1 mol of NaOH.
The number of moles of NaOH there is in 15.8 mL is calculated as follows:
0.321 mol/L x 1 L/1000 mL x 15.8 mL = 5.07 x 10⁻³ mol NaOH
Thus, we need 5.07 x 10⁻³ mol of HCl to react with 5.07 x 10⁻³ mol NaOH. We have a 0.631 M HCl solution. We calculate the volume of HCl we need by considering that 1 mol NaOH reacts with 1 mol HCl and that there are 0.631 moles of HCl in 1 liter of solution (1000 mL):
5.07 x 10⁻³ mol NaOH x 1 mol HCl/1 mol NaOH x 1000 mL/0.631 mol HCl = 8.04 mL
In the measurement 0.502 L, which digit is the estimated digit? A. 5 B. 3 C. The 0 to the left of the decimal point D. The 0 immediately to the left of the 3
Answer:
no c
Explanation:
Monomer liquid and polymer powder nail enhancement are service
Answer:
Monomer liquid and polymer powder nail enhancement are lucrative service
Calculate the mass percent of HOCH 2CH 2OH in a solution made by dissolving 3.2 g of HOCH 2CH 2OH in 43.5g of water.
Answer:
[tex]\%m/m=6.85\%[/tex]
Explanation:
Hello,
In this case, we are asked to compute the by mass percent for the given 3.2 g of ethylene glycol in 43.5 g of water. In such a way, since the by mass percent is computed as follows:
[tex]\%m/m=\frac{m_{solute}}{m_{solute}+m_{solvent}} *100\%[/tex]
Whereas the solute is the ethylene glycol and the solvent the water, therefore we obtain:
[tex]\%m/m=\frac{3.2g}{3.2g+43.5g} *100\%\\\\\%m/m=6.85\%[/tex]
Best regards.
Calculate the pH of a 0.10 M HCN solution that is 0.0070% ionized.
A) 1.00
B) 0.00070
C) 3.15
D) 5.15
E) 7.00
Answer:
D) 5.15
Explanation:
Step 1: Write the equation for the dissociation of HCN
HCN(aq) ⇄ H⁺(aq) + CN⁻(aq)
Step 2: Calculate [H⁺] at equilibrium
The percent of ionization (α%) is equal to the concentration of one ion at the equilibrium divided by the initial concentration of the acid times 100%.
α% = [H⁺]eq / [HCN]₀ × 100%
[H⁺]eq = α%/100% × [HCN]₀
[H⁺]eq = 0.0070%/100% × 0.10 M
[H⁺]eq = 7.0 × 10⁻⁶ M
Step 3: Calculate the pH
pH = -log [H⁺] = -log 7.0 × 10⁻⁶ = 5.15
The pH of the 0.10 M HCN solution that is 0.0070% ionized is 5.15 and the correct option is option D.
pH is a measure of the acidity or alkalinity of a solution. It is a logarithmic scale that indicates the concentration of hydrogen ions (H+) in the solution.
The pH scale ranges from 0 to 14, where a pH of 7 is considered neutral, pH values below 7 indicate acidity, and pH values above 7 indicate alkalinity.
The pH of a solution can be calculated using the formula:
pH = -log[H+]
Where [H+] represents the concentration of hydrogen ions in moles per liter.
Since HCN is a weak acid and only 0.0070% of it is ionized, assuming that the concentration of H+ ions is equal to 0.0070% of 0.10 M HCN.
0.0070% of 0.10 M HCN = (0.0070/100) × 0.10
= 0.000007 M
pH = -log(0.000007)
= 5.15
Thus, the ideal selection is option D.
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odor extensive or intensive
Answer:
Odour is intensive
Explanation:
intensive properties are Independent of the amount of matter
find the value of y in the equation Зу – 20 = 7.
[tex]3y-20=7\implies y=\frac{20+7}{3}=9[/tex].
Hope this helps.
y= 9
Explanation:
=> 3y - 20 = 7
=> 3y = 7+20
=> 3y = 27
=> y = 27/3
=> y = 9
HOPE OT HELPS. ◉‿◉
0.200 grams of HCl is dissolved in 0.801 grams water. The density of the solution formed is 1.10 g/mL. What is the molarity of the solution
Answer:
[tex]M=6.03M[/tex]
Explanation:
Hello,
In this case, since the molarity is computed by:
[tex]M=\frac{n_{solute}}{V_{solution}}[/tex]
Whereas the solute is the hydrochloric acid, we compute the corresponding moles with its molar mass (36.45 g/mol):
[tex]n_{solute}=0.200gHCl*\frac{1molHCl}{36.45gHCl} =0.00549molHCl[/tex]
Next, since the solution contains both HCl and water, we compute the volume in liters by using its density:
[tex]V_{solution}=(0.200+0.801)g*\frac{1mL}{1.10g} *\frac{1L}{1000mL} =9.1x10^{-4}L[/tex]
Therefore, the molarity turns out:
[tex]M=\frac{0.00549mol}{9.1x10^{-4}L}\\ \\M=6.03M[/tex]
Regards.
How much work does a gas do when it expands against a constant pressure of 0.600 atm from a volume of 50.00 mL to a volume of 440.00 mL?
Answer:
23.71J is the work that the gas do.
Explanation:
The work that a gas do under isobaric conditions follows the formula:
W = P*ΔV
Where W is work in atmL, P is the pressure and ΔV is final volume -Initial volume In Liters
Replacing with the values of the problem:
W = P*ΔV
W = 0.600atm*(0.44000L - 0.0500L)
W = 0.234atmL
In Joules (1atmL = 101.325J):
0.234atmL × (101.325J / 1 atmL) =
23.71J is the work that the gas do.
10.
17.0cm
23.0cm
4,00cm
A 38.6 kg marble slab is shown above. What is its density? Give your
answer to the nearest tenth.
g/cm3
Enter the answer
Check it
Answer:
Density, [tex]\rho=24.68\ g/cm^3[/tex]
Explanation:
Mass of a marble slab is 38.6 kg 38600 grams
The dimensions of the marble is 17 cm×23 cm×4 cm
We need to find its density. Mass per unit volume equals density. So,
[tex]\rho=\dfrac{m}{V}\\\\\rho=\dfrac{m}{lbh}\\\\\rho=\dfrac{38600\ g}{(17\times 23\times 4)\ cm^3}\\\\\rho=24.68\ g/cm^3[/tex]
So, the density of the marble slab is [tex]24.68\ g/cm^3[/tex]
A mixture containing only FeCl3 and AlClz weighs 5.95 g . The chlorides are converted to the hydrous oxides and ignited to Fe2O3 and Al2O3 . The oxide mixture weighs 2.62 g . Calculate the percent Fe and Al in the original mixture .
Answer:
The answer is "Al= 9.8% and Fe=18.0%"
Explanation:
Given:
The weight of [tex]FeCl_3\ and \ ALCl_3[/tex] = 5.95g
[tex]gFeCl_3=gFe (\frac{Mw\ FeCL_3}{\text{atomic weight of Fe}})\\\\gAlCl_3=gAl (\frac{Mw\ AlCL_3}{\text{atomic weight of Al}})\\\\[/tex]
[tex]\to a = FeCl_3+AlCl_3\\\\\to a=x+y \\\\ \to a= 5.95[/tex]
[tex]\to a =x \ gFe (\frac{Mw\ FeCL_3}{\text{atomic weight of Fe}})+ y \ gAl (\frac{Mw\ AlCL_3}{\text{atomic weight of Al}})\\\\[/tex]
[tex]\to x (\frac{162.2}{55.85})+ y (\frac{133.34}{26.98})= 5.95\\\\\to 2.90x+4.94y=5.95\\\\\ similarly \ for \ oxidies:\\\\\to 143x+1.89y=2.62\\\\\to x= 1.07 \ \ \ and \ \ y= 0.58\\\\\to \ Al \% = \frac{0.58}{5.95} \times 100= \bold{9.8} \%\\\\\to \ Fe \% = \frac{1.07}{5.95} \times 100= \bold{18.0} \%[/tex]
The mass of the compound has been given as the mass of each element in the compound. The percent Fe in the mixture is 18%, and the percent Al in the mixture is 9.8%.
What is the percent composition?The percent composition has been given as the mass of the element in the compound. The percent of iron and aluminum in their chlorides can be given as:
[tex]\rm Fe=Fe\;\times\;\dfrac{Mwt\;FeCl_3}{Mwt\;Fe}[/tex]
[tex]\rm Al=Al\;\times\;\dfrac{Mwt\;AlCl_3}{Mwt\;Al}[/tex]
The total mass of the compounds has been 5.95 grams.
Thus,
[tex]5.95=\rm FeCl_3+AlCl_3[/tex]
The mass of Fe and Al will be x and y of the mass in the compounds. Thus,
[tex]5.95=\rm x\;Fe\;\times\;\dfrac{Mwt\;FeCl_3}{Mwt\;Fe}\;+\;y\;Al\;\times\; \dfrac{Mwt\;AlCl_3}{Mwt\;Al}[/tex]
The oxides of the chemical has the sum of mass of 2.62 grams.
The mass of oxides can be given as:
[tex]2.62=\rm x\;Fe\;\times\;\dfrac{Mwt\;Fe2O_3}{Mwt\;Fe}\;+\;y\;Al\;\times\; \dfrac{Mwt\;Al_2O_3}{Mwt\;Al}[/tex]
Substituting the values of mass of Al, aluminum chloride, oxide, and Fe and its compounds.
[tex]\rm 2.90x+4.94y=5.95\\143x+1.89y=2.62[/tex]
Solving the equation, x = 1.07, and y = 0.58
The percent mass of the compounds has been given as the ratio of mass with compound mass.
Thus, the percent mass of Fe has been:
[tex]\rm Fe=\dfrac{1.07}{5.95}\;\times\;100\\ Fe=18\;\%[/tex]
The percent mass of Al has been:
[tex]\rm Al=\dfrac{0.58}{5.95}\;\times\;100\\ Al=9.8\;\%[/tex]
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Which measurement is best supported in units of microliters ?
The mass of an atom of uranium
The volume of a water droplet in a cloud
The thickness of a strand of hair
The volume of the Atlantic Ocean
Answer:the volume of a water droplet in a cloud
Explanation:
Answer:
The volume of a water droplet in a cloud
Explanation:
just took the test
Select the conjugate acid-base pair(s). a) HI, I b) HCHO2, SO4^2- c) CO3^2-, HCI d) PO4^3-, HPO4^2-
Answer:
d) PO4^3-, HPO4^2-
Explanation:
Basically, an acid and a base which differs only by the presence or absence of proton (hydrogen ion) are called a conjugate acid-base pair.
a) HI, I
This is incorrect. For the acid, HI the conjugate base is I⁻ ion.
b) HCHO2, SO4^2-
This is incorrect, there's no relationship between both entities.
c) CO3^2-, HCI
This is incorrect, there's no relationship between both entities.
d) PO4^3-, HPO4^2-
This is correct. The difference between both entities is the Hydrogen ion. This is the conjugate acid-base pair
You are comparing a reaction that produces a chemical change and one that produces a physical change. What evidence could you use to determine which type of change is occurring? \
Answer:
You are comparing a reaction that produces a chemical change and one that produces a physical change. What evidence could you use to determine which type of change is occurring?
If the reaction is a chemical change, new substances with different properties and identities are formed. This may be indicated by the production of an odor, a change in color or energy, or the formation of a solid.
Sample Response: If the reaction is a chemical change, new substances with different properties and identities are formed. This may be indicated by the production of an odor, a change in color or energy, or the formation of a solid.
What did you discuss in your response? Check all that apply.
the production of an odor
a change in energy
a change in color
the formation of a solid
the formation of new substances
a change in properties and identities
A chemical change may result in the following;
Evolution of gasChange in temperature of the reaction mixtureAppearance of a solidChange in colorA Physical change may result in the following;
Change in appearanceChange in sizeChange in shapeChange in textureA chemical change leads to the formation of a new substance. This implies that the composition of the substance has being changed.
A physical change does not lead to a change in the nature of the substance. However, the appearance, shape, texture or size of the substance may change.
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Predict the reactivity of silicon in water relative to that of sodium, magnesium, and aluminium. Explain your answer. How does the reactivity of the halogens vary within its own group from top to bottom?
Answer:
See explanation
Explanation:
The reactivity of metals has a lot to do with their position in the electrochemical series. However, it is also known that metallic character decreases across the period. This implies that as we move from left to right along the periodic table. Sodium, magnesium, aluminum and silicon continues to decrease in metallic character. As a matter of fact, silicon is a metalloid and not a pure metal.
Sodium reacts with cold water to give a vigorous reaction,magnesium and aluminium reacts with steam at red heat.
Silicon does not react with water, even as steam, under normal conditions.
Reactivity can be given as the ability of the atom to lose or gain electrons. The reactivity can be silicon is least as compared to sodium and other metals in water.
What is the trend of reactivity in the periodic table?The periodic table has the arrangement of the elements in groups and periods in the table.
On moving from left to right in the periodic table, the number of electrons in the same shell increase, thereby making the loss of electrons difficult. Thus, on moving from left to right in the periodic table, the metal reactivity decreases.
Hence, silicon present in the right most of the periodic table has the lower reactivity as compared to the sodium, magnesium, and aluminum on the left side of the periodic table.
In the periodic table, on moving from top to bottom, the number of shells increases, decreasing the force of attraction to the outermost electron. Thus, the metal reactivity increases down the group.
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A student is designing an experiment about the factors that affect math
grades. Which statement best represents a possible hypothesis for this
experiment?
O A. I think practicing math problems is the most important factor in a
student's math grade.
OB. If students spend at least 1 hour per night studying math, then
they will get a grade of 85 or higher.
C. Students who study more get higher math grades.
O D. Steve studied math for 1 hour every night and got a grade of 87.
Answer:
B. If students spend at least 1 hour per night studying math, then they will get a grade of 85 or higher.
Explanation:
A hypothesis is defined as a tentative or predictions or an educated guess of scientific questions. A hypothesis is always done before performing an experiment.
The correct hypothesis for the given experiment will be "If students spend at least 1 hour per night studying math, then they will get a grade of 85 or higher" because it has an if-then statement which is a conditional statement where statement after "if represents hypothesis" and "then represents conclusion".
Hence, the correct answer is "B. If students spend at least 1 hour per night studying math, then they will get a grade of 85 or higher."