There is a block on your desk that acts as a paperweight. Its measurements are 3 cm by 4 cm by 6 cm. The block has a mass of 184.32 g. What is the block made of? 

When a cracker dissolves in your mouth, then this is a chemical change. A chemical reactions is an atomic rearrangement-based chemical process.

An alteration of one or more compounds as one or maybe more new and distinct substances is referred to as a chemical change or chemical reaction. In other terms, a chemical reactions is an atomic rearrangement-based chemical process.

A chemical change normally cannot be reversed unless through additional chemical processes, although a physical change may frequently be done so. The power of the system changes when a chemical shift takes place. When a cracker dissolves in your mouth, then this is a chemical change.

Therefore, when a cracker dissolves in your mouth, then this is a chemical change.

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During the daytime, photosynthesis will occur while over a period of time carbon dioxide will accumulate as a result of respiration making it difficult for living things to survive.

It is defined as a process by which plants and other photosynthetic organisms convert the light energy in to chemical energy  through the process of cellular respiration.

Some of the energy which is converted  is stored in molecules of carbohydrates like sugar and starches  which are made up of from carbon dioxide and water . Photosynthetic organisms which can perform photosynthesis  are algae and cyanobacteria. Photosynthesis is largely responsible for producing and maintaining the content of oxygen in earth's atmosphere.

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In the PhET activity, "Properties of Gases", when pressure is kept the same and heat the volume increases. Therefore, option D is correct.

Charles' law states that if the pressure remains constant, the volume occupied by a fixed amount of gas is directly proportional to its absolute temperature.

This law states that a gas's volume and temperature have a direct relationship: as temperature rises, volume rises when pressure remains constant. When a gas is heated, the kinetic energy of the particles increases, causing the gas to expand.

Thus, option D is correct.

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1) number of valence electrons

2) number of principal energy levels

The periodic table is a tabular arrangement of the chemical elements, organized on the basis of their atomic number, electron configurations, and chemical properties. It is a useful tool for predicting the chemical behavior of an element and helps in understanding the relationships between elements and their chemical and physical properties.

The periodic table consists of rows and columns, where each element is placed in a specific position based on its atomic number and electron configuration. The elements in the same row (period) have similar electron configurations and exhibit similar chemical behavior, while the elements in the same column (group) have similar chemical and physical properties.

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The balanced chemical equation for the reaction is:

N2SO4 + 2NaOH → Na2SO4 + 2H2O

From the equation, we can see that for every 1 molecule of sodium sulfate (Na2SO4), 2 molecules of water (H2O) are produced. Therefore, to find the number of molecules of water produced, we need to determine the number of molecules of sodium sulfate produced in the reaction.

To do this, we need to use the molar mass of sodium sulfate and Avogadro's number. The molar mass of sodium sulfate is 142.04 g/mol, and Avogadro's number is 6.022 x 10^23.

The number of molecules of sodium sulfate produced in the reaction can be calculated as follows:

(2.0 g) / (142.04 g/mol) = 0.01405 mol

And the number of molecules of water produced can be calculated as follows:

0.01405 mol x 2 molecules/mol = 0.0281 x 6.022 x 10^23 molecules/mol = 1.69 x 10^23 molecules

Round 1.69 to 2.0 and your answer is  2.0 x 1023 molecules

Photosynthesis is the process in which plants use sunlight, water, and carbon dioxide to make oxygen and energy in the form of sugar. During each step of photosynthesis that is Sunlight absorption, Light-dependent reactions, Light-independent reactions explain in below description.

Sunlight absorption: Special pigments in photosynthetic cells absorb light energy. Plant pigment molecules absorb light with wavelengths ranging from 400 nm to 700 nm. This wavelength range is known as photosynthetically active radiation (PAR).

Light-dependent reactions: Light energy is used in light-dependent reactions to create two molecules required for the next stage of photosynthesis: the energy storage molecule ATP and the reduced electron carrier NADPH. Light reactions occur in the thylakoid membranes of chloroplast organelles in plants.

Light-independent reactions: Photosynthesis's light-independent reactions occur within the stroma. It contains enzymes that, in collaboration with ATP and NADPH, "fix" carbon from carbon dioxide into molecules that can be used to make glucose. The stroma also stores the chloroplast's own genetic material.

Thus, These are the steps of photosynthesis.

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3.32 × 10-⁵grams is equivalent to 33.2 micrograms.

Grams is a unit of mass equal to one-thousandth of a kilogram with a symbol of g.

Micrograms is unit of mass equal to one millionth of a gram, or 0.000 001 grams with a symbol of μg or mcg.

According to this question, we were given 3.32 × 10-⁵ micrograms. The conversion factor is as follows:

1 gram = 1000000 (1 × 10⁶) micrograms

Hence, 3.32 × 10-⁵ grams is equivalent to 33.2 micrograms.

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The nitrite and sulfite ions would change the colour after the addition of acidified potassium permanganate. Therefore, option A and D are correct.

An ion is a positively charged atom or molecule. It is charged because the number of electrons in the atom or molecule does not equal the number of protons.

Depending on whether the number of electrons in an atom is greater or less than the number of protons in the atom, an atom can acquire a positive or negative charge.

When potassium permanganate crystals are dissolved in water, a purple solution is formed. It is a strong oxidizing agent that does not produce toxic byproducts. It's usually made from other minerals like manganese oxide.

Thus, option A and D are correct.

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a. 225.0 has 4 significant figures.

b. 1000.0 has 4 significant figures.

c. 0.0003210 has 6 significant figures.

d. 0.0067 has 4 significant figures.

e. 1,000,000 has 7 significant figures.

f. 2.00001 has 6 significant figures.

Question 2

a. 15.9994 rounded to three significant figures is 16.0.

b. 1.0080 rounded to three significant figures is 1.01.

c. 0.6654 rounded to three significant figures is 0.665.

d. 4885 rounded to three significant figures is 4885.

e. 87,550 rounded to three significant figures is 88,000.

f. 0.027225 rounded to three significant figures is 0.0272.

Question 3

a. 77.981 x 2.33 = 181.081 (rounded to 3 significant figures)

b. 4 x 0.0665 = 0.266 (rounded to 3 significant figures)

c. 17,344,900 + 23.1 = 17,344,923.1 (rounded to 7 significant figures)

d. 9.80 - 4.762 = 5.038 (rounded to 3 significant figures)

e. 3.9 x 6.05 x 420 = 8,595.89 (rounded to 2 decimal places)

f. 14.1 / 5 = 2.82 (rounded to 2 decimal places)

g. 1001 + 16.23 = 1017.23 (rounded to 4 significant figures)

h. 424.5 + 2.8461 = 427.3461 (rounded to 4 decimal places)

i. 9.9 - 9.54 = 0.36 (rounded to 2 decimal places)

j. 7.3778 / 0.000265 = 27,864.345 (rounded to 3 decimal places)

k. (24.358) x (6.4) = 156.3712 (rounded to 4 decimal places)

(48.6) x (0.6959) = 33.88594 (rounded to 5 decimal places)

Significant figures of a number in positional notation are described as digits in the number that are reliable and necessary to indicate the quantity of something.

Decimal places on the other hand are described as positions of the digits to the right of a decimal point. Rounding numbers to decimal places is shortening a decimal number to a given degree of accuracy.

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In the electrolysis of brine, the gas collecting in the tube above the anode will be chlorine gas, which is greenish yellow in color.

Electrolysis is a process where an electric current is passed through a solution containing ions (called an electrolyte) to bring about a chemical reaction. This reaction splits the electrolyte into its component ions and distributes them to the electrodes (anode and cathode) connected to the source of electric current.

At the anode, negatively charged ions (anions) gain electrons and become neutral, while at the cathode positively charged ions (cations) lose electrons and become neutral. Chlorine gas is greenish yellow in color due to its chemical properties. When chlorine gas is formed at the anode during the electrolysis of brine, it is produced as a result of the oxidation of chloride ions (Cl-) present in the brine solution.

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The original concentration of the Pb(NO₃)₂ solution in mol/L would be 0.00036 moles / 0.64 L = 0.0000056 mol/L = 0.056 mM (rounded to 3 significant figures).

We must do a mass-to-moles conversion to ascertain the Pb(NO3)2 solution's initial concentration. The following equation describes the precipitation reaction between Pb(NO₃)₂  and H₂SO₄:

Pb(NO₃)₂ + H₂SO₄ -> PbSO₄ + 2HNO₃

PbSO₄ has a molar mass of 303.2 g/mol. 

Therefore, 0.00036 moles of PbSO₄ are equal to 0.109 g of PbSO₄  divided by 303.2 g/mol. 

Therefore, 0.00036 moles of PbSO₄ are equal to 0.109 g of PbSO₄  divided by 303.2 g/mol.  Since the ratio of Pb(NO₃)₂  to PbSO4 in the reaction is 1:1, we can infer that the initial solution included the same number of moles of Pb(NO₃)₂  

Since the ratio of Pb(NO₃)₂  to PbSO₄  in the reaction is 1:1, we can infer that the initial solution included the same number of moles of Pb(NO₃)₂   The Pb(NO₃)₂  solution's initial concentration would therefore be 0.00036 moles / 0.64 L = 0.0000056 mol/L = 0.056 mM. (rounded to 3 significant figures).

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The density of the fatty acid molecule is 8.71 g/mL

Fatty acids are the building blocks of the fat in our bodies and in the food we eat.

To calculate the density of the fatty acid molecule using dimensional analysis, we'll start with its molar mass and use Avogadro's number to convert to the number of molecules.

Then, we'll use the volume per molecule to find the total volume and divide the molar mass by the volume to find the density.

First, we'll convert the molar mass to grams per molecule:

235 g/mol / 6.022 x 10^23 molecules/mol = 235 g / (6.022 x 10^23) = 3.9 x 10^-23 g/molecule

Next, we'll find the total volume of the molecules by multiplying the number of molecules by the volume per molecule:

Volume = 4.48 x 10^-22 mL/molecule * 6.022 x 10^23 molecules/mol = 26.95 mL/mol

Finally, we'll divide the molar mass by the volume to find the density:

Density = 235 g/mol / 26.95 mL/mol = 8.71 g/mL

Therefore, The density of the fatty acid molecule is 8.71 g/mL

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Explanation:

To calculate the number of oxygen atoms in a sample of 288 amu, you would need to know the atomic mass of oxygen and the chemical formula of the sample.

Assuming that the sample is made of pure oxygen (O2), the atomic mass of oxygen is 16 amu. So, 288 amu / 16 amu/atom = 18 atoms of oxygen.

The density should be constant when the method of data collection is changed but it may increase error in measurement.

The method of data collection may affect the measurement because it increases the possibility of undesired errors during the process of experimentation and thus increases uncertainty.

Therefore, with this data, we can see that the method of data collection alters measurements in a given experimental and or observational procedure and may be seen to be affected by the errors in the case of different methodologies applied.

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The molecular weight of the ascorbic acid (vitamin C), given that 0.9 g of the acid was dissolved in 95 g of water is 170.7 g/mol

We'll begin by obtaining the mole of the ascorbic acid in the solution. Details below

Mole = Molality × mass of water (in kg)

Mole of ascorbic acid = 0.0555 × 0.095

Mole of ascorbic acid = 0.0052725 mole

Finally, we shall determine the molar mass of the ascorbic acid. Details below

Molar mass = mass / mole

Molar mass of ascorbic acid = 0.9 / 0.0052725

Molar mass of ascorbic acid = 170.7 g/mol

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Answer:

Explanation:

The velocity of electrons can be calculated using the equation v = h / (mλ), where h is Planck's constant (6.63 x 10^-34 Js), m is the mass of the electron, and λ is the wavelength of the radiation.

For sodium, the electron energy is given as Φ = 4.41 × 10–19 J. To find the velocity of the electrons, we first need to convert the energy into wavelength using the equation λ = hc / Φ, where c is the speed of light (3 x 10^8 m/s).

So, for sodium:

λ = hc / Φ = 6.63 x 10^-34 x 3 x 10^8 / 4.41 x 10^-19

λ = 290 nm.

And then using the velocity equation,

v = h / (mλ) = 6.63 x 10^-34 / (9.11 x 10^-31 x (290 x 10^-9))

For potassium, the electron energy is given as Φ = 3.68 × 10–19 J, and the wavelength can be calculated in the same way as for sodium:

λ = hc / Φ = 6.63 x 10^-34 x 3 x 10^8 / 3.68 x 10^-19

λ = 290 nm.

And then using the velocity equation,

v = h / (mλ) = 6.63 x 10^-34 / (9.11 x 10^-31 x (290 x 10^-9))

Note: m is the mass of an electron, which is 9.11 x 10^-31 kg.

So, both the velocity of the electrons from sodium and potassium would be the same, given that they are both exposed to the same wavelength radiation of 290 nm.

Answer:The velocity of electrons from sodium and potassium can be calculated using the equation E=hf, where E is the energy of the electron, h is Planck's constant and f is the frequency of the radiation.

From the equation E=hf, f can be calculated using the wavelength of the radiation:

f = c/λ

where c is the speed of light.

Then, using E=hf and the values for E (Φ) for sodium and potassium, the velocity of the electrons can be calculated using the equation:

v = sqrt(2E/m)

where m is the mass of the electron.

Explanation:

The velocity of electrons from sodium and potassium can be calculated using the equation E=hf, where E is the energy of the electron, h is Planck's constant and f is the frequency of the radiation.

From the equation E=hf, f can be calculated using the wavelength of the radiation:

f = c/λ

where c is the speed of light.

Then, using E=hf and the values for E (Φ) for sodium and potassium, the velocity of the electrons can be calculated using the equation:

v = sqrt(2E/m)

where m is the mass of the electron.

Answer:      1s2 3s1

Explanation:

Lithium is element number 3 so it has 3 electrons.  In the ground state, 2 electrons are in the 1s shell and 1 electron is in the 2s shell.

1s23s1    Correct answer.  2 electrons are still in the 1s shell, but the third electron has jumped to the 3s shell.

1s22s2   Wrong:  This atom has gained an additional electron in the 2s shell

1s2    Wrong:  This atom has lost  an electron.

1s22s1  Wrong:  This atom is in its ground state.

Answer:1s22s1

Explanation:

We can write down the electron configuration of bromine using the periodic table's building pieces.

The amount of electrons in each sublevel and energy level of the ground-state atom is displayed in the electron configuration of an atom. Start at the nucleus and add electrons one at a time until the total number of electrons equals the total number of protons in the nucleus to establish the electron configuration of a specific atom.

The lowest energy sublevel is awarded to each additional electron. The 1s sublevel will be the first to be filled, followed by the 2s and 2p sublevels, the 3s and 3p, the 4s and 3d, and so on. It may be crucial to understand how the electrons in an atom's partially filled sublevel are allocated throughout the orbitals.

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The number of molecules for 229 mg

The atomic mass from

Molecular mass is the sum of all the atomic mass in the compound.

According to Stoichiometry to calculate the number of moles of a compound

n = m ÷ M

X = n × L

Calculating the number of molecules

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the boiling point of pure X is 146.52 C.

As

ΔTb = Kb × m

ΔTb = Elevation in boiling point = Tb - T°b

m = Molality

So,

Tb - T°b = Kb × [tex]\frac{Wb . 1000}{Wa . Mb}[/tex]

Kb = 1.28

Wb = 16g of urea given

Wa = 150g of X

Mb = 60g = Molar mass of urea

Tb = 148.8 C

Putting values in Equation,

We get, the boiling point of pure X as 146.52 C.

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Lead is one example of a heavy metal. Cobalt and cadmium. They belong to a class of chemicals known as "heavy metals". The answer is option (c).

Lead is one example of a heavy metal. Cobalt and cadmium. They belong to a class of chemicals known as "heavy metals." Metallic substances with a relative high density when compared to water are referred to as heavy metals. Assuming that weight and toxicity are connected, heavy metals have included metalloids like arsenic, which can cause toxicity at low exposure levels.

Although heavy metals are generally found in nature and are necessary for life, they can become poisonous when they build up in organisms. Among the heavy metals that can poison the environment, arsenic, cadmium, and mercury are the most prevalent.

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The distribution coefficient measures the ratio of a compound's ionized and non-ionized species in a solution. Therefore, 1.57 is the distribution coefficient.

The distribution coefficient measures the ratio of a compound's ionized and non-ionized species in a solution of two separate immiscible phases. This phenomena can be designated as "D."

Here, water or perhaps an aqueous phase is basically one of the immiscible phases. Typically, the other phase is a hydrophobic phase that is inimical to water (or any other aqueous phase we use here). Because it is such a tiny value, we typically express it as a logarithmic value.

distribution coefficient = mass sorbed / mass of solid ÷ mass in solution/ volume of solution

distribution coefficient = 2.00g / 3.00g÷ 3.00g /70

                                    = 0.66/ 0.42

                                     =1.57

Therefore, 1.57 is the distribution coefficient.

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Equations are balanced using the idea of chemical reactions. to ensure that the reactant side and product side are in equilibrium the steps are below

Balancing chemical equations means making sure that the same number of atoms of each element are present on both sides of the equation. Here are the steps to balance a chemical equation:

It's important to keep in mind that the coefficients should be kept in their lowest whole number ratios, and you can use fractional coefficients if necessary. If the equation is already balanced, no further action needs to be taken.

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New moon is when the Moon cannot be seen because we are looking at the unit half of the Moon.

The new moon phase occurs when the Moon in directly between the Earth and Sun. A solar eclipse can only happen at new moon.

A waxing crescent moon is when the Moon looks like crescent and the crescent increases ("waxes") in size from one day to the next. This phase is usually only seen in the west.

The first quarter moon (or a half moon) is when half of the lit portion of the Moon is visible after waxing crescent phase. It comes a week after new moon.

A waxing Gibbous moon occurs when more than half of the lit portion of the Moon can be seen and the shape increases ("waxes") in size from one day to the next. The waxing gibbous phase occurs between the first quarter and full moon phases.

A full moon is when we can see the entire lit portion of the Moon.

The total lunar eclipse when the Moon is on the eclipse can only happen at opposite side of the Earth from the Sun, called opposition.

A lunar eclipse can only happen at full moon.

A waxing gibbous moon occurs when more than half of the lit portion of the Moon can be seen and the shape decreases ("waxes") in size from one day to the next. The waning gibbous phase occurs between the full moon and third quarter phases. after th

The full moon generally occurs on the 14th day after the new moon phase. The full moon occurs when the position of the earth is between the moon and the sun in a relatively straight line. The entire sunlit side of the moon becomes visible so that on a full moon, the moon looks completely round and very bright.

During the full moon many parts of the Moon can be seen from Earth, and most of it is the surface form in the form of craters. Because at full moon, some of the craters on the surface of the moon look like there are emission lines coming from the center of the crater.

These lines come from the scattering of particles that were thrown up when meteorites fell to the surface of the moon and formed craters.

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According to the stoichiometry of the given chemical equation, there are 4.502 mole of oxygen formed.

It is the determination of proportions of elements or compounds in a chemical reaction. The related relations are based on law of conservation of mass and law of combining weights and volumes.

Stoichiometry is used in quantitative analysis for measuring concentrations of substances present in the sample.

As per the equation 2 moles of potassium chlorate give 3 moles of oxygen , thus 367.8 g sample of  potassium chlorate is 367.8/122.55=2.99 moles 2.99 moles of  potassium chlorate  will give 2.99×3/2=4.502 moles.

Thus, there are 4.502 mole of oxygen formed.

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Answer:

Under magnification, the ovary contents appear as a mixture of clear, yellow, and pink liquid with small round cells. The cells are of varying sizes, some smaller than a human hair. There are also small, translucent, bubble-like structures present. The slide also shows small clusters of cells with a dark center.

Answer :Hydrophobicity is measured in terms of the contact angle of the water drops to the surface of textiles

Explanation:

One mole or 12 g of carbon reacts with one of oxygen molecule weighs 32 g will produce one mole of carbon dioxide. One mole of carbon dioxide weighs 44 g.

Carbon dioxide is an inorganic gas formed by the covalent bonding between carbon and oxygen gas. Carbon dioxide is an essential gas to maintain the living atmosphere in earth.

The balanced chemical equation of the reaction between oxygen gas and carbon is given below:

[tex]\rm C+O_{2} \rightarrow CO_{2}[/tex]

As per this equation, one mole of carbon reacts with one mole of oxygen gas:

Atomic mass of carbon = 12g

molecular mass of oxygen = 32 g

then molar mass of carbon dioxide = 32+ 12 = 44 h=g.

Therefore, 44 g of carbon dioxide is produced in this reaction.

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The amount, in grams of KCl that will be produced, would be 5.00 grams.

KClO3 decomposes when heated to produce KCl and O2 according to the following equation:

[tex]2KClO_3 -- > 2KCl + 3O_2[/tex]

Equivalent mole of 5.0 g KClO3 = 5/122.5 = 0.0408 mol

Since the mole ratio of KClO3 to KCl is 1:1, the mole of KCl formed will also be 0.0408 mol.

Mass of 0.0408 mol KCl = 0.0408 x 122.55

                                        = 5.00 grams

In other words, the mass of KCl that would be produced is 5.00 grams.

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