Answer:
D
Explanation:
Scientists always perform tests and observe and measure in the physical world to prove their points or answer their questions.
If you wanted to perform a controlled experiment to test the effect of temperature on the pressure of a bicycle tire, which of the following would be necessary?
In 1982, the United States government changed the way it minted pennies. Before 1982, pennies were made of 95% copper and 5% tin. Now they are made of 97.5% zinc coated with copper. Because they weigh different amounts (have different masses) and are still the same item, they make a good model for studying isotopes.
4. What do the two kinds of pennies represent in this exercise?
5. How do the pennies differ? How do isotopes differ?
6. What do the pennies have in common? What do isotopes have in common?
Which statement is a scientific law?
A.Scientists use genes to explain why evolution happens.
B.Genes are long patterns that are similar to computer codes.
C.A person’s traits are controlled by different forms of a gene.
D.The discovery of genes changed how scientists think about life.
Answer:
A.Scientists use genes to explain why evolution happens.
Explanation:
:)
describes the forces that exist
between a liquid and different
molecules,
A Adhesion
B. Repulsion
C. Condensation
D. Cohesion
98-2000 Anths Charpentine A Nights Arsenal
Answer:
i just answered this and its a
Explanation:
Ill give the brainliest answer to whoever helps me with this equation
Answer: The percent yield for the [tex]NaBr[/tex] is, 86.7 %
Explanation : Given,
Moles of [tex]FeBr_3[/tex] = 2.36 mol
Moles of [tex]NaBr[/tex] = 6.14 mol
First we have to calculate the moles of [tex]NaBr[/tex]
The balanced chemical equation is:
[tex]2FeBr_3+3Na_2S\rightarrow Fe_2S_3+6NaBr[/tex]
From the reaction, we conclude that
As, 2 moles of [tex]FeBr_3[/tex] react to give 6 moles of [tex]NaBr[/tex]
So, 2.36 moles of [tex]FeBr_3[/tex] react to give [tex]\frac{6}{2}\times 2.36=7.08[/tex] mole of [tex]NaBr[/tex]
Now we have to calculate the percent yield for the [tex]NaBr[/tex].
[tex]\text{Percent yield}=\frac{\text{Experimental yield}}{\text{Theoretical yield}}\times 100[/tex]
Experimental yield = 6.14 moles
Theoretical yield = 7.08 moles
Now put all the given values in this formula, we get:
[tex]\text{Percent yield}=\frac{6.14mol}{7.08mol}\times 100=86.7\%[/tex]
Therefore, the percent yield for the [tex]NaBr[/tex] is, 86.7 %
If 1.50 L of 0.780 mol/L sodium sulfide is mixed with 1.00 L of a 3.31 mol/L lead(II) nitrate solution, what mass of precipitate would you expect to form?
Answer:
336.1 g of PbS precipitate
Explanation:
The equation of the reaction is given as;
Na2S(aq) + Pb(NO3)2(aq) ----> 2NaNO3(aq) + PbS(s)
Ionically;
Pb^2+(aq) + S^2-(aq) -----> PbS(s)
Number of moles of sodium sulphide= concentration of sodium sulphide × volume of sodium sulphide
Number of moles of sodium sulphide= 0.780 × 1.5 = 1.17 moles
Number of moles of lead II nitrate= concentration of lead II nitrate × volume of lead II nitrate
Number of moles of lead II nitrate= 3.31× 1.00= 3.31 moles
Then we determine the limiting reactant. The limiting reactant yields the least amount of product.
Since 1 moles of sodium sulphide yields 1 mole of lead II sulphide
1.17 moles of sodium sulphide also yields 1.17 moles of lead II sulphide
Hence sodium sulphide is the limiting reactant.
Thus mass of precipitate formed= amount of lead II sulphide × molar mass of sodium sulphide
Molar mass of lead II sulphide= 287.26 g/mol
Mass of lead II sulphide = 1.17 moles × 287.26 g/mol
Mass of lead II sulphide= 336.1 g of PbS precipitate
What is the decay mode of radium-226?
Answer:
Radium-226 is a radioactive decay product in the uranium-238 decay series and is the precursor of radon-222. Radium-228 is a radioactive decay product in the thorium-232 decay series. Both isotopes give rise to many additional short-lived radionuclides, resulting in a wide spectrum of alpha, beta and gamma radiations.
Potassium atoms contribute one eletron to metallic bonding,but calcium atoms contribute two eletrons .Explain which metal is likely to be harder
Answer:
potassium is likely to be harder
Explanation:
because whenan atom loss electron they can form particle ion acquare stable a arrangement that loos electron can transfer to another which that also to acquaire stable
Rapid, uncontrolled cell division of abnormal cells is characteristic of
sex cells
cancer
growth
sexual reproduction
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.
Substitute natural gas (SNG) is a gaseous mixture containing CH4(g) that can be used as a fuel. One reaction for the production of SNG is
4CO(g) + 8H2(g) → 3CH4(g) + CO2(g) + 2H2O(l) ΔHo = ?
Use appropriate data from the following list to determine ΔHo for this SNG reaction.
C(graphite) + 1/2O2(g) → CO(g) ΔHo = -110.5 kJ
CO(g) + 1/2O2(g) → CO2(g) ΔHo = -283.0 kJ
H2(g) + 1/2O2(g) → H2O(l) ΔHo = -285.8 kJ
C(graphite) + 2H2(g) → CH4(g) ΔHo = -74.81 kJ
CH4(g) + 2O2(g) → CO2(g) + 2H2O(l) ΔHo = -890.3 kJ
Answer:
ΔH° of the reaction is -747.54kJ
Explanation:
Based on gas law, it is possible to find the ΔH of a reaction using ΔH of half reactions.
Using the reactions:
(1) C(graphite) + 1/2O₂(g) → CO(g) ΔH° = -110.5 kJ
(2) CO(g) + 1/2O₂(g) → CO₂(g) ΔH° = -283.0 kJ
(3) H₂(g) + 1/2O₂(g) → H₂O(l) ΔH° = -285.8 kJ
(4) C(graphite) + 2H₂(g) → CH₄(g) ΔH° = -74.81 kJ
(5) CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(l) ΔH° = -890.3 kJ
The sum of 4×(4) + (5) gives:
4C(graphite) + 8H₂(g) + 2O₂(g) → CO₂(g) + 2H₂O(l) + 3CH₄(g)
ΔH° = -74.81 kJ ×4 - 890.3 kJ = -1189.54kJ
Now, this reaction - 4×(1) gives:
4CO(g) + 8H₂(g) → CO₂(g) + 2H₂O(l) + 3CH₄(g)
ΔH° = -1189.54kJ - 4×-110.5 = -747.54kJ
Thus ΔH° of the reaction is -747.54kJ
ΔH° of the reaction is for the production of SNG -747.54kJ
Hess law and enthalpyAccording to Hess’ law of constant summation, the standard reaction enthalpy is independent of the pathway or number of the reaction steps taken for a multistep reaction, rather it is the sum of standard enthalpies of intermediate reactions involved at the same temperature.
Based on Hess law, it is possible to find the ΔH of a reaction using ΔH of half reactions.
From the given reactions:
C(graphite) + 1/2O₂(g) → CO(g) ΔH° = -110.5 kJCO(g) + 1/2O₂(g) → CO₂(g) ΔH° = -283.0 kJH₂(g) + 1/2O₂(g) → H₂O(l) ΔH° = -285.8 kJC(graphite) + 2H₂(g) → CH₄(g) ΔH° = -74.81 kJCH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(l) ΔH° = -890.3 kJThe sum of Reaction 4 × 4 + Reaction 5 - Reaction 1 × 4 gives the reaction below:
4CO(g) + 8H₂(g) → CO₂(g) + 2H₂O(l) + 3CH₄(g)
ΔH° = {-74.81 kJ × 4} - 890.3 kJ {- 4 ×-110.5}
ΔH° = -747.54kJ
Therefore, ΔH° of the reaction is for the production of SNG -747.54kJ
Learn more about enthalpy and Hess' law at: https://brainly.com/question/9328637
what is the mass of 3.01x1023 atoms of iron(atomic mass of fe=56)
Answer:
mass=279grams
Explanation:
GIVEN DATA
number of atoms=3.01×10^23
avogadro's number=6.022×10^22
molar mass of iron=56g/moles
TO FIND
mass in gram of iron=?
SOLUTION
by using the formula
mass in gram=(number of atoms÷avogdro's number)×molar mass
mass=(3.01×10^23÷6.022×10^23)×56
mass=0.499×56
mass=27.9grams=28 grams