True or False
If the answer is true, write "true" on the line. If the answer is false, replace the underlined word
or phrase with one that will make the sentence correct. Write the new word(s) on the line
Forming a hypothesis is the first step of the scientific method​

Answer:

The answer to your question is:  3.276 x 10³¹ Joules

Explanation:

Energy from the sun: 7.80 x 10²⁷ kcal

Look for the factor to convert units

Rule of three to convert units

                   1 cal ----------------------   4.2 Joules

           1000 cal ---------------------     x

 x = (1000 x 4.2) / 1 = 4200 Joules

                   1 kcal ----------------   4200 Joules

               7.8 x 10²⁷ kcal -------     x

           x = (7.8 x 10²⁷ x 4200) / 1 = 3.276 x 10³¹ Joules

Answer:

251 g of compound contain 2.39 moles.

Explanation:

Given data:

mass of compound Al(CN)3 = 251 g

moles = ?

Solution:

First of all we will calculate the molar mass of given compound.

molar mass of Al(CN)3 = 26.98 + (26 × 3)

molar mass of Al(CN)3 = 105 g/mol

Formula:

number of moles = mass/ molar mass

number of moles = 251 g / 105 g/mol

number of moles = 2.39 mole

Answer:

The minimum number of significant digits in 828,000,000 is 3.

Explanation:

This is because there are 3 non-zero digits that are considered significant.

The minimum number of significant digits in 828,000,000 is three.

In the given number, all non-zero digits (8, 2, and 8) are considered significant digits. The zeroes in this case are placeholders and do not contribute to the number's significant digits.

Therefore, the minimum number of significant digits in 828,000,000 is three, as it is determined by the count of non-zero digits in the number.

This explanation emphasizes the rules for identifying significant digits in a value, focusing on the actual non-zero digits that convey meaningful information.

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Answer:

B) Observations and experimentation

Explanation:

this is the most suitable words to describe how is Science used in describing the world. we collect the  knowledge in organized way and provide it with explanations and start to predict about the future world

ِAny Inventions are based on Science and no Inventions without Observations and experimentation

No one of us have went to a chemistry or a physics labs without using Observations and experimentation

Answer:

5 g of heptane were burned.

Explanation:

Given data:

Mass of CO₂ produced = 15.5 g

Mass of heptane burned = ?

Solution:

Balance chemical equation:

C₇H₁₆ + 11O₂ →7CO₂ + 8H₂O

First of all we will calculate the moles of CO₂ produced.

Number of moles = mass / molar mass

Molar of CO₂ = 44 g/mol

Number of moles = 15.5 g / 44 g/mol

Number of moles = 0.3523 mol

Now we will compare the moles of CO₂ and C₇H₁₆ from balance chemical equation

                     CO₂      :     C₇H₁₆

                      7         :        1

                 0.3523     :        1/7 × 0.3523 = 0.05 mol

Mass of C₇H₁₆:

Number of moles = mass / molar mass

Mass = number of moles ×  molar mass

Mass =  0.05 mol / 100 g/mol

Mass = 5 g

Answer:electrons indicates to the no of protons because they are same in number.

Explanation:

Answer:

The mass of 16.3 moles of nickel is 956. 647 g.

Explanation:

Given data:

moles of nickel = 16.3 mol

molar mass of nickel = 58.69 g/mol

mass in gram = ?

solution:

Formula:

number of moles = mass / molar mass

mass = number of moles × molar mass

mass = 16.3 mol × 58.69 g/mol

mass= 956. 647 g

To find the mass of 16.3 mol of nickel, multiply the number of moles by the molar mass of nickel, 58.693 g/mol, resulting in a mass of 956.9 grams.

To find the mass in grams of 16.3 mol of the element nickel (Ni), you need to use the element's molar mass. As identified in the information provided, the molar mass of nickel is 58.693 g/mol. Applying this molar mass to the given number of moles (16.3 mol), you can calculate the mass as follows:

Mass = number of moles × molar mass

Mass = 16.3 mol × 58.693 g/mol

Mass = 956.8969 g

Therefore, the mass of 16.3 mol of nickel is 956.9 grams (rounded to one decimal place).

Answer:

When you have those kind of compounds you have to multiply each element inside the bracket by the subscript outside the bracket. Here you have 1 Pb, 2 N and 6 O.

Explanation:

Answer:

Replace the formulas inside the parentheses with single letters  

Explanation:

Here's an equation with lots of parentheses.

(NH₄)₃PO₄ + Pb(NO₃)₂ ⟶ NH₄NO₃ + Pb₃(PO₄)₂

It looks impossible to balance, doesn't it?

One way to balance the equation is to recognize that the polyatomic ions (the formulas inside the parentheses) stay together.

Then we can make some substitutions.

Let A = NH₄, X = PO₄, and Y = NO₃

Then the equation becomes

A₃X + PbY₂ ⟶ AY + Pb₃X₂

Here's how to balance it.

1. Start with the most complicated formula, Pb₃X₂, and put a 1 in front of it.

A₃X + PbY₂ ⟶ AY + 1Pb₃X₂

2. Balance Pb

We have fixed three atoms of Pb on the right, so we need three atoms of Pb on the left. Put a 3 in front of PbY₂.

A₃X + 3PbY₂ ⟶ AY + 1Pb₃X₂

3. Balance X

We have fixed two atoms of X on the right, so we need two atoms of X on the left. Put a 2 in front of A₃X.

2A₃X + 3PbY₂ ⟶ AY + 1Pb₃X₂

4. Balance A

We have fixed 6 atoms of A on the left, so we need 6 atoms of A on the right. Put a 6 in front of AY.

2A₃X + 3PbY₂ ⟶ 6AY + 1Pb₃X₂

Every formula has a coefficient, and the equation is now balanced.

Next, we replace the original formulas in the equation.

The balanced equation is

2(NH₄)₃PO₄ + 3Pb(NO₃)₂ ⟶ 6NH₄NO₃ + 1Pb₃(PO₄)₂

c. protons and neutrons are the two particles found in the nucleus of an atom

A proton is a subatomic particle found in the nucleus of every atom

Protons and neutrons are in the center of the atom, making up the nucleus. Electrons surround the nucleus. Protons have a positive charge. Electrons have a negative charge. The charge on the proton and electron are exactly the same size but opposite.

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Answer:

C

Explanation:

just took quiz

Answer:

42 m/s

Explanation:

To we convert units for speed we can use dimensional analysis. First thing we do is seperate the measurement into a fraction. After this we can multiply by 1km over 0.62137 miles. We do this so that the miles cancel out.

[tex]\frac{95mi}{h}[/tex] × [tex]\frac{1km}{0.62137mi}[/tex] = [tex]\frac{95km}{0.62137h}[/tex]

After this we can use a conversion factor and divide by 3.6.

[tex]\frac{95km}{0.62137h}[/tex] ÷ 3.6 = 42 m/s

Answer:

Ursus: genus

Arctos: Species

Explanation:

If you think of the way the chart flows from the most broad to the most specific: kingdom, phylum/division, class, order, family, genus, species, you see that genus name comes first then the species name.

Lithium chloride solution most likely shows a vivid colour.

Answer: Option D

Explanation:

Flame test, an analytical strategy in chemistry to find certain elements, like metal ions, on the basis of characteristic emission spectrum of each element.

Because each element has a well-defined spectrum of linear emission, scientists can recognise it by the colour of the flame they produce.

For example, lithium and strontium red flame, nickel chloride appears as a brown or green solid, the potassium salt in the flame gives a characteristic purple colour, and hydrogen chloride as acid, a colourless gas.  Colour's dense in the order as blue > red > green > yellow.

Final answer:

The potential energy stored in a spring is proportional to the square of the displacement (x) from its undeformed position, as expressed by the formula PE_s = ½ kx².

Explanation:

The potential energy on a spring is proportional to the square of the displacement (x) from its undeformed position. When a spring is stretched or compressed by a distance x, the work done is stored as potential energy. This energy can be expressed by the formula PE_s = ½ kx², where k is the spring's force constant. At maximum compression or stretch, all the energy in the spring is potential, and when the spring passes through the equilibrium point, it possesses kinetic energy, which is also proportionate to the square of the amplitude of the motion.

Answer:

The question to your answer is:

Explanation:

Data

mass = 521 g

Water volume = 50.0 ml

Increase of water = 77 ml

Formula

density = mass / volume

First substract the final volume to the initial volume

Volume of gold = 77 - 50 = 27 ml

Now, use the formula

density = 521 / 27 ml = 19.3 g/ml

The density of the gold nugget is 19.3 g/mL.

To find the density of the gold, we need to calculate the volume of the gold nugget from the water displacement and then divide the mass of the gold by this volume. The volume of the gold nugget can be determined by calculating the difference in the water level before and after the gold was added. This value is 77.0 mL - 50.0 mL = 27.0 mL. Since the density (d) can be calculated using the formula d = mass/volume, we can substitute the given mass of 521 g and the calculated volume of 27.0 mL to find the density.

Using these values gives us: density = 521 g / 27.0 mL = 19.3 g/mL.

Therefore, the density of the gold is 19.3 g/mL, which is consistent with the known density of gold.

Answer:

The branch of chemistry that best describes the chemist´s work is organic chemestry

Explanation:

The chemist wants to improve the process for natural gas, a mix of organic compuond, mainly alcans.

A research to find the better way to process natural gas after it is removed from the ground is a work in organic chemistry.

Organic chemistry deals with organic compounds, their properties, reactions, uses etc. The organic compounds are hydrocarbons and its derivatives contain  carbon chains attached with hydrogen in the backbone.

Natural gases are hydrocarbons like methane, propane, butane etc. They comes under organic chemistry. All other compounds other than hydrocarbons and their derivatives are inorganic.

Hence, the research work on natural gas comes in organic chemistry thus, option A is correct.

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Answer:

it is The fuel used for fusion is abundant in nature and easy to obtain and The fusion process doesn’t require an energy input  ans Fusion has fewer safety risks than fission. and Fusion doesn’t produce radioactive waste products.

Explanation:

Answer:

The correct answer is option 5.

Explanation:

The process of nuclear fission takes place due to the dissociation of heavy atoms into lighter atoms, generating high energy particles in the procedure like alpha, neutrons, and beta particles. On the other hand, the process of nuclear fusion takes place by combining lighter atoms into heavier atoms generating very less radioactive constituents.  

In the process of nuclear fusion, there are also lesser chances of a meltdown of a fusion reaction in comparison to a fission reaction, thus, minimizing the occurrences of an accident. The process of nuclear fusion is better in comparison to nuclear fission in generating electricity in power plants as fusion processes do not generate radioactive waste components.  

In the process of nuclear fission, one projectile is required to hit the heavy element nucleus, and the reaction cannot be stopped and always generate radioactive elements as the side component. While in nuclear fusion an enormous amount of heat is required. The reaction can be stopped readily and the eventual component produced is not radioactive in nature, that is, environment-friendly.  

Answer:

Absorption and emission spectra

Explanation:

This is occurs when an atom either absorbs or emits energy when bombarded by a source.

Neils Bohr predicted that electrons moves round in the atom in distinct orbitals according to their energy. An electron in its ground state can become excited if it gains sufficient energy which surpasses that of its ground state configuration. An atom can also move from higher energy levels to lower ones. During the descent, energy is given off in form of emission spectra.

Absorption occurs when electrons in an atom absorbs energy from incoming radiation and they re-radiate it in all directions. This is given off as a spectra and can be observed for such electron.

Final answer:

Quantum mechanics replaced the idea of electrons moving in fixed orbits with the concept of orbitals, where electrons have a high probability of being found. Evidence for this includes distinct atomic spectra and quantum numbers that match experimental data.

Explanation:

The question about the behavior of electrons around the nucleus is a fundamental concept in chemistry and physics. The early model by Niels Bohr suggested that electrons move in definite circular paths or orbits around the nucleus, akin to planets orbiting the sun. However, this model was succeeded by quantum mechanics, which describes electron behavior as a set of probabilities rather than definite paths.

Quantum mechanics introduced the concept of electron orbitals, which describe regions of space around the nucleus where there is a high probability of finding an electron. One piece of experimental evidence is the atomic spectra, which show distinct lines corresponding to electrons moving between energy levels in an atom. This indicates that electrons occupy specific energy states rather than moving randomly.

Another supporting evidence comes from quantum numbers, which describe the properties of electron orbitals and help explain the arrangement of electrons in atoms. These quantum numbers arise naturally from the equations of quantum mechanics and match a vast array of experimental data.

Answer:

The percent composition of Protium( H¹) in nature is 99.21%.

The percent composition of Deuterium (H² )in nature is 0.79%.

Explanation:

Atomic mass of protium is 1.

Atomic mass of deuterium is 2.

These are two isotopes of hydrogen that make the total abundance of hydrogen in nature while third isotope tritium is radio active and unstable its abundance is 0%.

First of all we will set the fraction for both isotopes H¹ and H²

X for the isotopes having mass 2 amu.

1-x for isotopes having mass 1 amu.

The average atomic mass of hydrogen is 1.0079.

we will use the following equation,

2x + 1 (1-x) = 1.0079

2x + 1 - 1x = 1.0079

2x- 1x = 1.0079 - 1

1x = 0.0079

x= 0.0079/1

x= 0.0079

Percent abundance of H².

0.007 × 100 = 0.79 %

0.79% is abundance of H² because we solve the fraction x.

now we will calculate the abundance of H¹.

(1-x)

1-0.0079 =0.9921

Percent abundance of H¹.

0.9921 × 100= 99.21 %

99.21% for H¹.

The average atomic mass of hydrogen is 1.0079, which suggests that the most common isotope is H-1, but there is also a smaller amount of H-2 in nature. The specific percent composition would require more information to determine.

The average atomic mass of an element is the weighted average of the atomic masses of its naturally occurring isotopes. The fact that the average atomic mass of hydrogen is 1.0079 indicates that the most abundant isotope in nature is H-1 (hydrogen-1 or protium) which has an atomic mass close to 1. However, H-2 (hydrogen-2 or deuterium) is also present in nature, but in smaller amounts, as its atomic mass is close to 2. The slightly higher than 1 average atomic mass takes into account these two isotopes' presence and their relative abundances.

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Answer:

Meanwhile

Explanation:

Think of a comic book, or a superhero show, you usually see the protagonist, or the hero, doing something like saving an innocent pedestrian, or helping a little old lady across a street, then the screen will flash and say 'meanwhile' which means while this was happening, this was also happening.

An example could be in The Wizard of Oz, when Dorothy is walking with her friends through The Haunted Forest, you see the Wicked Witch of the East, peering through her crystal ball, unto Dorothy. To summarize what was happening you could say,

'Meanwhile, as Dorothy and her friends walked through The Haunted Forest, The Wicked Witch watched their stroll.'

Really hopes this helps!

Answer:

CL

because cleetus will rule the world

Answer:

[tex]\frac{1}{4}[/tex]

Explanation:

From the given problem, we are to find the factor number by which the volume of the compressed gas has changed through.

We apply Boyle's law to this problem because the condition of the reaction stipulates a constant temperature.

Boyle's law states "the volume of a given mass of gas is inversely proportional to its pressure provided that temperature remains constant". Mathematically, it is expressed as:

                           P₁V₁ = P₂V₂

P₁ is initial pressure on the gas

V₁  is the initial volume of the gas

P₂ is the final pressure of the gas

V₂ is the final volume of the gas

From the problem, we are to find the factor through which the volume changed:

             P₁V₁ = P₂V₂

              V₂ = [tex]\frac{P_{1} }{P_{2} } V_{1}[/tex]

Now:

P₁ =  P₁

P₂ = 4P₁

                V₂ = [tex]\frac{P_{1} }{4P_{1} } V_{1}[/tex]

Therefore, the factor of the volume change is [tex]\frac{1}{4}[/tex]

The study of chemicals and bonds is called chemistry.

The correct answer is option A which is 1/4.

From the given problem, we are to find the factor number by which the volume of the compressed gas has changed. We apply Boyle's law to this problem because the condition of the reaction stipulates a constant temperature.

Boyle's law states "the volume of a given mass of gas is inversely proportional to its pressure provided that temperature remains constant". Mathematically, it is expressed as:

P₁V₁ = P₂V₂

Where

From the problem, we are to find the factor through which the volume changed:

  P₁V₁ = P₂V₂

V₂ = [tex]\frac{P_1}{P_2}*V_1[/tex]

Now:

P₁ =  P₁

P₂ = 4P₁

Hence

V₂ = [tex]\frac{P_1}{4P_2}*V_1[/tex]

Therefore, the factor of the volume change is 1/4.

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Answer:

V= 37.0 mL

Explanation:

First find the moles of the known substance (CuCl2)

n= cv

where

n is moles

c is concentration

v is volume ( in litres)

n= 0.108 × 0.0946

n=0.0102168

Using the mole ratio in the balanced reaction, we can find the moles of Na3PO4

n (Na3PO4)= n (CuCl2) × 2/3

=0.0102168 × 2/3

=0.0068112

Now we have all the necessary values to calculate the volume

v=n/c

v= 0.0068112/0.184

v= 0.0370173913 L

v= 37.0 mL

37 ml volume of 0.184 M Na₃PO₄ solution is necessary to completely react with 94.6 mL of 0.108 M CuCl₂ solution.

The molarity is the way to express the concentration of the solution. The molarity of any solution can be calculated by dividing the number of mos of solute by the volume of the solution in liters. The unit of the molarity of the solution is mol/L or represented by M.

Given the chemical equation of precipitation reaction:

2Na₃PO₄ (aq)  +  3CuCl₂ (aq) →  Cu₃(PO₄)₂ (s) +  6NaCl (aq)

Given the volume of 0.108 M CuCl₂ solution = 94.6 ml = 0.946 L

The number of moles of CuCl₂ = M ×V = 0.108 × 0.846 = 0.01022 mol

If 3 moles of CuCl₂ completely react with Na₃PO₄  = 2

Then 0.01022 moles of  CuCl₂ will react with Na₃PO₄ :

= (2/3) × 0.01022

= 0.00681 mol

The volume of 0.184 M of Na₃PO₄ required = 0.00681 /0.184 = 37 ml

Therefore, 37 ml of Na₃PO₄  solution is required to completely react with 94.6mL of 0.108 M CuCl₂.

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Answer:

pressure and volume

Explanation:

Boyle's law states that the volume of a fixed mass of gas is inversely proportional to it's pressure at constant temperature.

Answer:

D. pressure and volume

Explanation:

Boyle’s law states that,

For a given amount of a gas, Pressure is inversely proportional to its volume at constant temperature

Thus the expression is

PV = constant (T and n are constant)

When there is a change in pressure and volume we make use of the expression  

[tex]P_1 V_1=P_2 V_2[/tex] (T and n are constants)

Where [tex]P_1[/tex] and [tex]V_1[/tex] are the Initial pressure and volume and

[tex]P_2[/tex] and [tex]V_2[/tex] are the final pressure and volume

Inversely proportional means when one increases the other one decreases. That is as per Boyle’s law when Pressure increases the volume will decrease and vice versa.

Using the formula for density (mass/volume), it's determined that the density of carbon dioxide gas is 0.00196 g/mL, the block of wood is 1 g/mL, and the irregular stone is 5 g/mL.

To answer these density problems, we use the formula: density = mass/volume.

1. For carbon dioxide gas, the mass is 0.196 g and the volume is 100 mL. Therefore, the density equals 0.196/100 = 0.00196 g/mL.

2. For the block of wood, the volume is the cube of the side length (3 cm x 3 cm x 3 cm = 27 cm^3 = 27 mL, as 1 cm^3 = 1 mL). The mass is 27 g, so the density equals 27/27 = 1 g/mL.

3. The irregular stone displaces water volume from 2.0 mL to 7.0 mL, which gives a total volume of 5.0 mL. Mass is 25 g, so the density equals 25/5 = 5 g/mL.

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Answer:

Nitrogen

Explanation:

Answer:

Explanation:

#9 Sodium (Na) - 0.15% - Sodium is an important electrolyte. Like potassium, it is used for nerve signaling. Sodium is one of the electrolytes that helps regulate the amount of water in the body.

Answer:

Options (1), (4) and(5)

Explanation:

The earth's lithosphere is divided into two types of crust, that are commonly known as-

Both the type of crust are comprised of water, rock as well as soil. The rocks of oceanic crust are much younger than the continental crust because the oceanic crust is formed from the seafloor spreading where the new materials are added to the crust along the mid-oceanic ridge. The rocks at this boundary are the youngest. On the other hand, the continental crust is the oldest and is present from the time of the formation of the earth. The denser oceanic crust subducts below the lighter continental crust in a convergent plate boundary.

Thus, the correct answers are options (1), (4) and(5).

Answer:the answers are 1,4 and 5

Explanation:hope this helps

Answer:

The answer to your question is: 3

Explanation:

If an atom has 5 electrons, 5 neutrons and 5 protons, it means that the element is Boron. Boron is situated in the third group A, that means that is has 3 elements in its outermost shell.

Also, if we do the electronic configuration:

                                                                         1s² 2s²2p¹

If we count the number of electron in the second level of energy, the result will be:    2 in s and 1 in p  = 3. Those are the valence electrons.

Answer:

3.783×10²⁴

Explanation:

We know that one mole of water contain two moles of hydrogen atom and one mole of oxygen atom. shown in following equation:

                         2H₂ + O₂ → 2H₂O

And  

1 mole of hydrogen = 6.022×10²³ atoms of hydrogen

The number 6.022×10²³ is called Avogadro number and it is the number of atoms in one mole of substance. While we have to find the hydrogen atoms in 3.14 moles of water

So the factor 3.14 given in the question contain  

3.14×2×6.022×10²³ number of hydrogen atoms which is equal to the 3.783×10²⁴.

Answer:

1.89×10^24 atoms

Explanation:

I mole of hydrogen molecule contains 6.02×10^23 atoms. This is known as the Avogadro's number. The Avogadro's number gives the number of elementary entities contained in one mole of a substance.

One mole of a substance is the amount of that substance that contains the same number of elementary entities as 12g of C-12

Hence 3.14 moles of hydrogen will contain 3.14 ×6.02×10^23= 1.89×10^24 atoms

Final answer:

A pi bond is formed by the side-by-side overlap of unhybridized 2pz orbitals on the carbon and the oxygen.

Explanation:

The pi bond is formed by the side-by-side overlap of unhybridized 2pz orbitals on the carbon and the oxygen. Just like in alkenes, the 2pz orbitals that form the pi bond are perpendicular to the plane formed by the sigma bonds.