Which phrase is evidence of the limits of what science can study?
This question is incomplete; here is the complete question:
Which phrase is evidence of the limits of what science can study?
A. Only a phenomenon that a scientist can observe with instruments
B. Only a phenomenon that a scientist can observe without instruments
C. Only a phenomenon that a scientist will be able to explain with certainty
D. Any phenomenon that a scientist can observe or model
The correct answer is D. Any phenomenon that a scientist can observe or model
Explanation:
Science focuses on phenomena that can be objectively studied or witnessed. This includes any phenomenon a scientist can register using observation, instruments, or that can be represented through models. This is because, through observations or instruments, it is possible to prove the phenomenon occurs and understand how this happens; also, models can represent or recreate the phenomenon itself, which is essential to understand and explain the phenomenon. Moreover, science has an objective focus and due to this, aspects such as personal beliefs that cannot be represented through a model or be observed are not part of science. According to this, the correct answer is D.
the simplest formula for a compound made from element X(molar mass=79.0g mol) that is 21.0% nitrogen by mass is ___
A. XN
B. XN2
C.X2N2
D.X3N2
Answer:
C
Explanation:
Compounds are substances that are made of elements linked by chemical bonds. "The simplest formula for a compound made from element X that is 21.0% nitrogen by mass is X₂N₃." Thus, option C is correct.
What is the empirical formula?The empirical formula has been the representation of the ratio of the whole number of atoms involved to make a molecule or compound. It has been calculated by calculating the moles through mass and, molar mass.
The elements involved are X (unknown), and N (known).
Given,
Mass percentage of nitrogen = 21.0% = 21 gms
Mass percentage of X = 100.0 % - 21.0 % = 79.0% = 79 gms
Molar mass of X = 79.0 g /mol
Molar mass of Nitrogen = 14 g/mol
Moles of X is calculated as:
Moles X = 79 ÷ 79
= 1 mol
Moles of N are calculated as:
Moles N = 21 ÷ 14
= 1.5 mol
Now, the moles are divided by the smallest mole as:
X = 1 ÷ 1 = 1
N = 1.5 ÷ 1 = 1.5
The ratios are 1:1.5 or 2:3. 2X and 3N.
The empirical formula for the compound will be X₂N₃.
Therefore, the simplest formula for the compound will be X₂N₃.
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0.400 mole of sucrose, C 12H 22O 11, contains ________ C atoms.
Answer:
2.89x10²⁴ atoms of Carbon are contained in 0.400 moles of sucrose
Explanation:
The formula of sucrose is C₁₂H₂₂O₁₁, that means per mole of sucrose you will have 12 moles of carbon. In 0.400 moles of sucrose you will have:
0.400 moles Sucrose * (12 moles C / 1 mole Sucrose) = 4.8 moles of Carbon
To convert moles to atoms you must use Avogadro's number (1 mole contains 6.022x10²³ atoms):
4.8 moles Carbon * (6.022x10²³ atoms / 1 mole) =
2.89x10²⁴ atoms of Carbon are contained in 0.400 moles of sucrose0.4 mole of sucrose, C₁₂H₂₂O₁₁ contains 2.89×10²⁴ carbon atoms
How to determine the mole of carbon1 mole of C₁₂H₂₂O₁₁ contains 12 mole of C.
Therefore,
0.4 mole of C₁₂H₂₂O₁₁ will contain = 0.4 × 12 = 4.8 mole of C
How to determine the atoms of carbonFrom Avogadro's hypothesis,
1 mole of C = 6.02×10²³ atoms
Therefore,
4.8 mole of C = 2.89×10²⁴ atoms
Thus, 0.4 mole of sucrose, C₁₂H₂₂O₁₁ contains 2.89×10²⁴ carbon atoms
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What is the density of an unknown metal that has a mass of 157.4 g and a volume of 20 mL?
Answer:
7.87g/mL
Explanation:
density=mass/volume
density=157.4/20
density=7.87g/mL
Determine which physical conditions are necessary to support nuclear fusion and formation of stars.
Answer:
The correct approach will be "Increased gravitational attraction".
Explanation:
The increased gravitational attraction seems to be the natural or physical phenomenon that is required to promote nuclear reactions including star formation. This is much more important to establish stars at different temperatures (lower) and greater magnetic pull as well as nuclear fusion tends to happen.My barometer is reading 1253 torr. What is the pressure in mmHg?
A. 1.253
B. 1.649
C. 1253
D. 1649
Answer:
The pressure in mmHg is 1253 (option C)
Explanation:
Two quantities are directly proportional if when multiplying or dividing one of them by a number, the other is multiplied or divided by that number. In other words, the magnitudes are directly proportional when one magnitude increases and so does the other in the same proportion; or when one magnitude decreases and so does the other in the same proportion.
The rule of three or is a way of solving proportionality problems between three known values and an unknown value, which can be applied to directly proportional quantities as follows:
a ⇒ b
c ⇒ x
So [tex]x=\frac{c*b}{a}[/tex]
where a, b and c are data and x is the unknown value to be calculated.
In this case, knowing that 1 Torr = 1 mmHg, the rule of three can be applied as follows: if 1 torr is equal to 1 mmHg, 1253 torr is equal to how many mmHg?
[tex]pressure=\frac{1253 torr*1 mmHg}{1 torr}[/tex]
pressure= 1253 mmHg
The pressure in mmHg is 1253 (option C)
what happens when the net forces are the same, do you add or subtract it
Answer:
If two forces act on an object in the same direction, the net force is equal to the sum of the two forces.
Explanation:
google is my explanation
Answer:
Answered by Oreo!
Explanation:
So a net force is the sum of all forces acting on an object! The question u asked is if the net forces are the same, do u add or subtract it.. <= the answer to that would be:
If it’s the same than the net force is the sum of the forces...
The net force = to the sum of two forces
Hope this helps! Sorry if something didn’t go right, I’m new to brainly! :)
A farmer applies 1455 kg of a fertilizer that contains 10.0% nitrogen to his fields each year. Fifteen percent (15.0%) of the fertilizer washes into a river that runs through the farm.If the river flows at an average rate of 0.175 cubic feet per second, what is the additional concentration of nitrogen (expressed in milligrams of nitrogen per liter) in the river water due to the farmer's fertilizer each year?
Answer:
the additional concentration of nitrogen in the water = 0.1396 mg/L
Explanation:
Given that a farmer uses 1455 kg of fertilizer → 10% nitrogen
15% of the fertilizer is said to be washed into the river,
i.e.
(15/100) × 1455 = 218.25 kg
The amount of nitrogen molecule in the washed fertilizer is :
10% of 218.25 kg
= (10/100) × 218.25 kg
= 0.1 × 218.25 kg
= 21.825 kg in a year.
The river flows at an avg. rate of 0.175 ft³/sec
Then the amount of river water in a year = [tex]0.175 \dfrac{ft^3}{sec}\times 3.155 \times 10^7 \ sec[/tex]
since 1 ft³ = 28.3168 L
the amount of river water in a year = [tex]0.175(28.3168)\times 3.155 \times 10^7 \ L[/tex]
the amount of river water in a year = 156344132
The concentration of nitrogen molecule= mass/volume
= [tex]\dfrac{ 21.825 \times 10^6 \ mg}{ 156344132 \ \ L }[/tex]
= 0.1396 mg/L
Thus, the additional concentration of nitrogen in the water = 0.1396 mg/L
general characteristics of coinage metals
Answer:
Characteristics. They are all relatively inert, corrosion-resistant metals. Copper and gold are colored. These elements have low electrical resistivity so they are used for wiring.
Explanation:
Hope this help u
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Question 3 of 10
Which of the following is an example of a phase change from liquid to solid?
A. Ice melting
B. Water freezing
C. Water evaporating
D. Water condensing
Answer:
the answer is B
Explanation:
B is the answer
PLEASE HELP WILL MARK BRAINLIEST!!!!!!!!
Explanation:
1. 4×10^5
2. 6×10^-4
3. 2.1995×10^7
4. 5.050×10^-2
5. 7280
6. 0.00003608
7. 940.9
8. 0.0015
Marks as brainest
Answer:
not sure
Explanation:
Which of the following solutions is basic?a. [H3O+] = 1.0 x 10-10 Mb. [OH-] = 1.0 x 10-10 Mc. [H3O+] > 1.0 x 10-7 Md. [OH-] < 1.0 x 10-10 Me. [OH-] = 1.0 x 10-7 M
Answer:
[H3O+] = 1.0 x 10-10
Explanation:
A basic solution is any solution whose pH is above 7.0.
If we carefully calculate the pH of each of the species listed among the options, we will discover that it is only [H3O+] = 1.0 x 10-10 that has a pH of 10.0. This pH corresponds to a basic solution. Hence the solution having [H3O+] = 1.0 x 10-10 is a basic solution.
how many cg are equal to 0.459kg
1kg = 100000
0.459kg = 0.459*100000
= 45900cg
→ 0.459kg = 45900cg
According to unit conversion and as 1 kg=100,000 cg , there are 45900 cg in 0.459 kg.
What is unit conversion?Unit conversion is defined as a multi-step process which involves multiplication or a division operation by a numerical factor.The process of unit conversion requires selection of appropriate number of significant figures and the rounding off procedure.
It involves a conversion factor which is an expression for expressing the relationship between the two units.A conversion ratio always has value which equals to one which indicates that numerator and denominator have values which are expressed in different units.
It is an easy process which involves unit conversion between the different conversion systems. While unit conversion care needs to be taken regarding accuracy and precision.
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What is most likely to occur when jagged edges of rock plates grind past each other?
Answer:
The most likely to occur when jagged edges of rock plates grind past each other is the presence of a high degree of frictional force.
This may cause the rocks to be broken down into smaller particles.
It also implies that the energy necessary for further disintegration and movement of rocks is stored up.
unit processes in charge of smelting
Answer:
Smelting, process by which a metal is obtained, either as the element or as a simple compound, from its ore by heating beyond the melting point, ordinarily in the presence of oxidizing agents, such as air, or reducing agents, such as coke.
Hope I helped!
Explanation:
Good's buffers are compounds that are useful near neutral pH. MES buffer has pKa of 6.15, MOPS has pKa of 7.5, and HEPPS has pKa of 8.0.Required:Identify which Good's buffers are most effective near pH 7.0 and near pH 6.0.
Answer:
MES for pH near to 6.0 and MOPS for pH near to 7.5.
Explanation:
Hello,
In this case, given that the Henderson-Hasselbach equation is:
[tex]pH=pKa+log(\frac{[Base]}{[Acid]} )[/tex]
Good's buffers are those having pKa's near to the required pH since we look for a [Base]/[Acid] ratio to approach 1, thus, for a pH near to 7.0 a good buffer may be MOPS as it has a pKa of 7.5 and for a pH neat to 6.0 a good buffer may be MES as it has a pKa of 6.15.
Best regards.
If the atom has a MASS of 127 and 45 NEUTRONS, then it contains how many
PROTONS

Answer:
53
Explanation:
because minus 3
Which one correctly lists the compound that has the highest boiling point from each group it belongs to? Group I: SiH 4, SnH 4, CH 4, and GeH 4 Group II: HCl, HBr, HF, and HI Group I: SiH4 and Group II: HF Group I: SnH4 and Group II: HF Group I: SnH4 and Group II: HI Group I: CH4 and Group II: HI Group I: CH4 and Group II: HF
Answer:
Group I: SnH4 and Group II: HF
Explanation:
In the case of group 14 hydrides, we know that the melting and boiling points of compounds increase down the group. Since the melting and boiling points of compounds increase down the group, SnH4 will have the highest boiling point.
In the case of group 17 hydrides, we know that electro negativity decreases down the group. As electro negativity decreases, so does the magnitude of hydrogen bonding among group 17 hydrides. Hence, HF has the highest boiling point among group 17 hydrides since it has the greatest magnitude of hydrogen bonding between its molecules.
An automobile tire contains air at 320.×103 Pa at 20.0 ◦C. The stem valve is removed and the air is allowed to expand adiabatically against the constant external pressure of 100.×103 Pa until P = Pexternal. Assume the air is an ideal gas with C¯ V = 5/2 R (diatomic). Calculate the final temperature.
Answer:
6.15.3 k
Explanation:
From the question we can see that
q = 0, Δu = w
Then,
[tex]T_f = \frac{C_{V,m}+RP_{ext}P_i}{C_{V,m}+RP_{ext}P_f} T_i[/tex]
putting values wet
=[tex]\frac{2.5\times 8.314+8.314\left(10^5\right)\left(3.20\times 10^5\right)}{2.5\times 8.314+\left(8.314\right)\left(10^5\right)\left(10^5\right)}\times \:293[/tex]
T_f = 615.3 K
Which element is the
most reactive?
A . Silicon
B. oxygen
C. lithium
D . Aluminum
Which of the following species is the least nucleophilic?A) (CH3)3NB) BF3C) H2OD) (CH3)3CO-E) CN-
Answer:
BF3
Explanation:
BF3 possesses an open sextet. This implies that the octet around the central atom is incomplete. As a result of this, BF3 will function as an electrophile rather than as a nucleophile.
Hence of all the compounds listed in the options, BF3 is the least nucleophillic.
Select the numbers that show how the numbers given in scientific notation can be added. 2.00 times 10 to the negative 26th power minus 3.34 time 10 to the negative 27th power. Below that, a math example: 2.00 x 10 to the negative 26th power minus A time 10 to the B power equals C times 10 to the D power. A = B = C = D =
Answer:
A = 0.334
B = -26
C = 1.666
D = -26
Explanation:
just took quiz
Answer:
A = ✔ 0.334
B = ✔ -26
C = ✔ 1.666
D = ✔ -26
Explanation:
edge 2023
Strontium-90 is radioactive and has a half life of 28.8 years. How much of a 2.90mg sample would be left after 137. years?
Round your answer to 2 significant digits. Also, be sure your answer has a unit symbol.
Answer:
0.11 mg
Explanation:
From the question given above, the following were obtained:
Half life (t½) = 28.8 years
Original amount ((N₀) = 2.90 mg
Time (t) = 137 years
Amount remaining (N) =?
Next, we shall determine the rate of disintegration (K). This can be obtained as follow:
Rate of decay (K) = 0.693/ half life (t½)
K = 0.693 / t½
Half life (t½) = 28.8 years
Rate of decay (K) =?
K = 0.693 / t½
K = 0.693 / 28.8
K = 0.0241 /year
Finally, we shall determine amount remaining after 137 years as follow:
Original amount ((N₀) = 2.90 mg
Time (t) = 137 years
Rate of decay (K) = 0.0241 /year
Amount remaining (N) =?
Log (N₀/N) = kt/2.3
Log (2.9/N) = 0.0241 × 137 / 2.3
Log (2.9/N) = 3.3017 / 2.3
Log (2.9/N) = 1.4355
Take the antilog of 1.4355
2.9/N = antilog (1.4355)
2.9/N = 27.26
Cross multiply
2.9 = N × 27.26
Divide both side by 27.26
N = 2.9/27.26
N = 0.11 mg
Therefore, the amount remaining after 137 years is 0.11 mg
How many molecules are in 237 g (about a cup) of water? a. 1513.1 b. 4267 c. 6.02 * 1023 d. 93 * 1024 e. 7.93 * 10 24
Answer:
7.93E24 molecules of water
Explanation:
determine no. of moles of water: 237 g/18 g/mole H2O= 13.17 moles H2O
13.17 moles H2O x 6.02E23 molecules/mole= 7.93E24 molecules of water
Mole measure the number of elementary entities of a given substance that are present in a given sample. Therefore, 7.93×10²⁴ molecules are in 237 g (about a cup) of water. The correct option is option E.
What is mole?The SI unit of amount of substance in chemistry is mole. The mole is used to measure the quantity or amount of substance. We know one mole of any element contains 6.022×10²³ atoms which is also called Avogadro number.
Mathematically,
number of moles of water=237 g÷18 g/mole
number of moles of water = 13.17 moles
number of atoms/molecules=number of moles × 6.022×10²³(Avogadro number)
molecules of water=13.17 moles x 6.02×10²⁴
molecules of water=7.93×10²⁴ molecules of water
Therefore, 7.93×10²⁴ molecules are in 237 g (about a cup) of water. The correct option is option E.
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why do scientists store oxygen and hydrogen in water?
Answer:
When molecular hydrogen (H2) and oxygen (O2) are combined and allowed to react together, energy is released and the molecules of hydrogen and oxygen can combine to form either water or hydrogen peroxide. ... For both of the reactions shown, the hydrogen molecules are oxidized and the oxygen atoms are reduced.
Explanation:
Which statements are true about triangle ABC and it’s translated image, ABC? Select two options.
what is the molar mass of PbCO₄
Answer:
283.211
Explanation:
. Answer the following: 7 x 2 = 14
1. Find
1. Find
2/3÷4
Explanation:
2/3 ÷ 4 = 0.166
I think this should be the answer
Explanation:
[tex] \frac{2}{3} \div 4[/tex]
[tex]make \: 4 \: as \: \frac{1}{4} \: since \: is \: divide[/tex]
[tex] \frac{2}{3} \times \frac{1}{4} [/tex]
[tex] \frac{2}{12} = \frac{1}{6} [/tex]
Hope this is correct and helpful
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help me ill give brainliest i need help with a b c d and to see if i got propene and methane right please help :(
Answer:Yes, you got it right
Explanation:
Pls give brainliest
What period is Zn (zinc) in?
O A. 2A
O B. 12
O C. 30
D. 4
Answer:
D. 4
Explanation:
