which test tubes are controls in the experiment?

A galaxy is a huge group of collection of dust, gas and billions of stars and their solar systems.

What is a galaxy?

A galaxy is the group of starts and some other objects of the space held together by gravity. The universe consists of more than 100 billion galaxies.  A lot of dark matter is also found in the galaxies.

The galaxy where earth is present is called the milky way. Almost all the galaxies are thought to contain a supermassive blackholes at the center of the galaxies. The milky way is a spiral galaxy which has the disk, the nucleus and the halo. They contain stars, moons, comets, planets, neutron stars, dust and black holes.

Therefore, galaxy is a grouping of dust, stars, moons, comets and more than a billion stars with a black hole in the center held together by the gravity.

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Alkali metals are more reactive metal . Potassium is more reactive than other elements, so option D is correct.

The alkali metals in group 1 are so-called because when their oxides and hydroxides are treated with water, the resulting solutions are alkaline. As a result of the creation of the hyroxide ion, the solution becomes basic or alkaline.

Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Ru), Cesium (Cs), and Francium are alkali elements.

Potassium is more electropositive element and its enthalpy is increases, so potassium is more reactive than other elements.

Thus, option D is correct.

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Explanation:

Hydrogen sulfide H2 S has the sulfur atom in the center with two individual hydrogen atoms covalently bonded to a central sulfur atom. The bonded and lone pairs of electrons will orient as far as possible giving a tetrahedral electron geometry.

A plant giving off oxygen during photosynthesis comes from water .

The plants takes up the carbon dioxide and the water and in the presence of sunlight  releases the oxygen as the by product in the process of the photosynthesis. in the process of the photosynthesis , the chlorophyll excited by the sunlight. in the presence of this the water undergoes the photolytic oxidation. this means that water is breaking down in to the hydrogen ion , electrons and the free oxygen. there are various experiments that shows that the source of oxygen is the water.

Thus, A plant giving off oxygen during photosynthesis comes from water .

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The possibility of the removal of the electron from an atom using electrical forces was supported by plum pudding model by J. J. Thomson.

What is plum pudding model?

Plum pudding model was first discovered by J. J. Thomson in the year 1904 after the discovery of electrons. This model depicts that the electrons are embedded in the the pool of positive charges in the atom. It was called plum pudding model because the electrons were like the plums in the positively charged atom like a pudding.

According to the plum pudding model by J. J. Thomson, the electrons are embedded on the positively charged particles in the atom. These electrons can be removed by applying a particular voltage of electric forces from the atoms.

Therefore, plum pudding model of J. J. Thomson supported the removal of electron from the atom by applying electric force.

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The atomic mass of an atom if its mass is approximately equal to carbon-12 will be 12 and in case of 4.5 times carbon-12 will be 54

Atomic mass of an element is the average mass of the atoms of an element which are measured in atomic mass unit. Or we can also say that the atomic mass is actually the weighted mass is a weighted average of all of the isotopes of elements, in which the mass of each element is multiplied by the abundance of that particular isotope.

So the atomic mass of an atom if the mass is approximately equal to carbon-12 then the mass of the element will be equal to 12 as the atomic mass of carbon-12  is 12.

where as the atomic mass of an atom if its mass is approximately equal to 4.5 times as much as carbon-12 will be ⇒ 4.5×12= 54

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The estimated effective nuclear charge, Zeff, that an electron in an atom of chlorine experiences is seven.

The net positive charge that an electron in an atom experiences is known as effective nuclear charge. The overall positive charge of the nucleus is typically higher than the effective nuclear charge (nuclear charge). The inner orbital electrons' protective shielding effect is responsible for the electron's reduction in nuclear charge.

We use the following formula to determine Z eff for electron:

Z eff is equal to Z - S, where S is the average electron density between the nucleus and the electrons under consideration and Z is the number of protons in the nucleus.

Thus, Zeff = 17 - 10 (core electrons) = 7

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Moles of chromium (III) oxide is produced when 34.69 g Cr reacts with excess oxygen gas is 0.67 mole.

When oxygen combines with detail or compound, an oxidation response occurs. Oxidation also can be defined because of the manner in the elimination of hydrogen from the reactant species. Oxidation is the process of dropping electrons by using a molecule, atom, or ion.

Calculation:-

Cr + 3 0₂ - 2 Cr₂O3

Molar mass of chromium is  =  52

mole =  mass / molar mass

       = 34.69 / 52

   =  0.67 mole

When a reactant loses electrons for the duration of a response, it's far known as oxidation. whilst a reactant accumulates electrons throughout a reaction, it's miles known as reduction. when metals react with acid, that is a common incidence. while a reactant loses electrons all through a response, it is referred to as oxidation.

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12.4 kJ of heat is required melt 37.2 g of ice at (0 °C)

What is Latent heat?

The equation is used to establish a relationship between how much heat is involved when a number of moles of a substance undergoes a phase change.

Equation for heat flow at constant temperature and pressure:

  q = n *ΔH

where

q = amount of heat ?

n = no of moles

ΔH = enthalpy  ( 6.02 kJ/ mol)

For water, the molar enthalpy of fusion is 6.02 kJ/ mol. It means , in order to convert 1 mol of solid ice at 0 °C to water at 0° C , we need to impart 6.02 kJ of heat

We know

 n = w / M.M

n = moles

w = given mass ( 37.2 g )

M.M = molar mass ( molar mass of water)

n = 37.2 / 18

   = 2.06

Substituting:

q = n * ΔH

   = 2.06 * 6.02

   = 12.401 kJ

Rounding to 3 significant figures., q = 12.4 kJ

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Semiconductor materials are categorized as insulators if their band gaps are bigger than 3 and 5 eV.

Due to the low but finite band gap energy of semiconductor materials, an electron can easily transition from the valence band to the conduction band in the presence of external thermal energy. A semiconductor material's typical band gap energy range is 0.5eV–3eV.

Wide-bandgap materials have bandgaps above 2 eV, in contrast to conventional semiconductors like silicon, whose bandgaps are in the range of 0.6 to 1.5 eV.

In a p-type semiconductor, holes make up the majority of the carriers while electrons make up the minority.

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Carbon C diamond is one form of carbon; the other is graphite.

The correct option is A.

Both graphite and diamond are carbon allotropes. Although graphene and fullerenes are among the rarer unusual allotropes of carbon, they do exist. An enormous three-dimensional network of carbon atoms makes up a diamond.

A chemical equation is a phrase that enumerates a compound's component elements and their respective weights. If there is just single atom of a particular sort, no subscript is necessary. If an atom contains three or more of a specific type of atom, a subscript is appended to a symbol for that atom.

Chemical equations provide details about the chemical composition of a compound. They also represent the proportions in which the compound's individual components come together to create the compound. The chemical formula of a compound is crucial when describing it in a chemical equation.

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Answer:

electrons are combining with other electrons

The pH of a solution prepared by dissolving 5.00 g of ammonium perchlorate in 200.0 mL of water is less than pH 1.

calculation:-

Weight of NH4Cl 4 = 5g

Volume of water = 200ml

NH4clo4 Molecules Height = 117.499/ mok

First, we have to find Concentrations like Molarity

M = N/V(ml)x1000

M = wt/m.wt x 1000/v(m)

5/117-49 ×1900/200

= M = 0.212 ≅ 0.2

PH = -log [H+]

= -log [0.2]

= -log [2x[tex]10^{-1}[/tex]]

= 4  -10g2

= 1 - 0.3010

PH = 6990

pH < 1

Ammonium perchlorate is an odorless white sandy powder. Used in analytical chemistry and as an etching and engraving agent. It is also used in animal fats and explosives. Ammonium perchlorate is on the Dangerous Goods List as cited by the DOT and NFPA. This substance is a strong oxidizing agent. Reacts violently with combustible and reducing materials and metals.

This produces toxic and corrosive fumes including ammonia and hydrogen chloride. Risk of fire or explosion. Ammonium perchlorate is produced by the reaction of ammonia and perchloric acid. This process is the main outlet for the industrial production of perchloric acid. Salts can also be prepared by salt metathesis reaction of ammonium salts with sodium perchlorate.

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Answer:

174 milliliters of the first brand and 116 milliliters of the second brand

Explanation:

equation:

0.06x+0.11(290-x)=0.08(290)

translation:

6% concentration of x milliliters plus 11% concentration of 290-x milliliters equals 8% concentration of 290 milliliters

solve for x (which is the volume of the first brand):

0.06x+0.11(290-x)=0.08(290)

0.06x+31.9-0.11x=23.2

-0.05x+31.9=23.2

-0.05x=-8.7

x=174

174 milliliters of the first brand and 290-174=116 milliliters of the second brand

 In a physical change, the appearance or form of the matter changes but the kind of matter in the substance does not. However, in a chemical change, the kind of matter changes, and at least one new substance with new properties is formed.

The mole ratio of acid to base when neutralizing hydrochloric acid with sodium hydroxide is 1:1. A mole of NaOH would completely neutralize one mole of HCl.

The mole ratio would be 2:1 if the hydrochloric acid and barium hydroxide were to be combined instead. Assuming they react in a 1:1 ratio in accordance with the balanced neutralization equation, the moles of acid and base are identical at the equivalence point in a neutralization. Using the reaction between solutions of hydrochloric acid and sodium hydroxide as an example, let's examine how a neutralization reaction creates both water and a salt. This reaction's general equation is NaOH + HCl H2O and NaCl.

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In order to determine a chiral molecule, it is checked if the molecule has one or more stereocenters.

Chiral molecules are molecules whose mirror images cannot be superimposed on each other.

Chiral molecules have a chiral center or a stereocenter.

The chiral center of the stereocenter in a chiral molecule is the central atom to which four different chemical species are bonded.

The general rule to determine a chiral molecule is to check for at least one chiral center or stereocenter in the molecule.

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The dimensions that will maximize the volume held by the can r= 5.23 cm, S = 37.1 cm².

Given, Height = 10.84 cm, radius of the base = 5.42 cm and material for the surface =37 square cm.

Let the height be h and the base's radius be r.

Then, volume V= πr²h= 1000cc

and surface area of the can,

S= 2πr²+ 2πrh

Now, eliminating h,

S= S(r)= 2π(r²+ 1000/ πr²)

r= (1000/ 2π)^1/3= 5.23 cm, nearly.

Correspondingly, h= 10.84 cm, nearly

There is no maximum for S. Also,

S''= 2π(2+ 3000πr4)>0.

For this r= 5.23 cm, S = 37.1 cm²

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The effective nuclear charge of the electron in the least tightly bound orbital is  3.97.

The term photoelectron spectroscopy is a type of spectroscopic technique that is useful when we want to determine the different positions of an electron in an atom. This is why we have to look at the ionization energy of the electron when we are looking at the valence shell.

We know that;

IE = 13.6 Zeff/n^2

IE = ionization energy

n = Shell where the valence electron is found

Zeff = effective nuclear charge

Substituting values;

Zeff = IE * n^2/13.6

Zeff = 6 * (3)^2/13.6

Zeff = 3.97

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The number of SO2 molecules in 2.32 mol of SO2  is 1.39 × 10²³ molecules.

given that :

number of moles of SO₂ = 2.32 mol

Avogadro's number = 6.022 × 10²

number moles can be calculated by the following formula :

number of moles = mass / molar mass

number of molecules of SO² in 2.32 moles is given as :

number of molecules of SO₂ = 2.32 mole × 6.022 × 10²³ molecules / mole

number of molecules of SO₂ =  1.39 × 10²⁴ molecules.

Thus, The number of SO2 molecules in 2.32 mol of SO2  is 1.39 × 10²⁴ molecules.

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Answer:

See below

Explanation:

Ideal gas law    PV = n R T

P = 2.3 atm

V = 2.6 L

n = ?

R = .08205  L atm / (mole K)

T = 26 + 273.15  K

Plugging in the numbers     finds   n = .244 moles

The  IUPAC names of the given organic compounds are as follows:

Organic compounds are compounds that are derived from living organisms or from the remains of living organisms.

The main elements present in organic compounds are carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorus

One class of organic is hydrocarbons which are compounds composed of only hydrogen and carbon.

The given organic compounds are hydrocarbons. An example is octane.

The names of organic compounds follow the IUPAC naming convention.

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Magnesium is oxidized in a crucible with airborne oxygen, and the masses prior to and following the oxidation are recorded.

Its primary application is as a bleaching in the production of paper and fabric, but is also used to create rubber, pesticides (insecticides), and solvents. To destroy hazardous bacteria, chlorine is added to drinking water & swimming pool water.

Low levels moderate chlorine exposure can irritate the eyes, throat, and nose. Breathing air chlorine gas at higher concentrations can damage the lung by changing breathing, producing coughing, & changing breathing rate. Severe additional effects can result from chlorine exposure. Chlorine exposure may be harmful to workers.

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The total heat that is involved in this change is  23632.5 J.

We know that energy is involved as matter is changing from one state to another and in this case what we have is a 75g sample of liquid water at 10°C ends up as ice at -10°C.

There are are about three steps of the change in the energy;

1) Heat required until the water would change to ice

2) Latent heat of fusion of ice

3) Heat required until the temperature drops to -10°C

Thus;

1) H = mcdT

m = mass of the water

c = specific heat capacity of water

dT = temperature change

H = 75 * 4.18 * (0 - 10)

H = -3135 J

2) Heat of fusion =

H = mL

m = mass of ice

L = latent heat of fusion of ice

336 J g^-1 *  75g

= 25200 J

3) Heat required to decrease the temperature futher

H = 75 * 2.09 * (0 - (-10))

H = 1567.5J

Total heat required = 25200 J + 1567.5J  -3135 J

= 23632.5 J

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Answer:A particular mineral is defined by its chemical composition and crystalline structure.

Explanation:

Statement which is true about minerals is that a  particular mineral is defined by its chemical composition and crystalline structure.

Minerals are defined as a chemical compound which has a well -defined composition and possesses a specific crystal structure.It occurs naturally in the pure form.

If a compound occurs naturally in different crystal structure then each structure is considered as a different mineral.The chemical composition of a mineral varies depending on the presence of small impurities which are present in small quantities.

Some minerals can have variable proportions of two or more chemical elements which occupy equivalent position in the crystal structure.It may also have variable composition which is split into separate species.

Physical properties of minerals include color,streak, luster,specific gravity and cleavage.

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Blue litmus paper turns red. xH2O is heated it decomposed to produce HCl which is the cause for a change in color.

Blue litmus paper is mainly used for acid testing. It turns red when it comes in contact with acid. It remains blue in contact with basic or neutral substances. The dye in blue litmus reacts with the H+ ions and is chemically changed so that the bonds are tuned to reflect longer wavelength light, appearing red to our eyes.

A simple way to measure pH is to use litmus paper. When litmus paper is touched it changes color depending on whether the paper is acidic or basic. If the paper turns red it is acidic if it turns blue it is basic. There is no reaction when blue litmus paper is placed on the pad, so there is no change in the blue litmus paper.

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The partial pressure of nitrogen is 0.59 atm and the partial pressure of oxygen is 0.29 atm.

given that :

pressure = 101.3 kpa = 0.99 atm = 1 atm

volume of nitrogen = 2 dm³ = 2 L

volume of oxygen = 1 dm³ = 1 L

Temperature = 273 K

using ideal gas equation , we get

P V = nRT

moles of nitrogen = P V / RT

                              = ( 1 × 2 )/  0.082 × 273

                              =   2 / 22.38

                              = 0.08 mol      

moles of oxygen = ( 1 ×1 ) / 0.082 × 273

                             = 0.04 mol

now, P V = n RT

P = n RT /V

partial pressure of nitrogen = ( 0.08 × 0.082 × 273 ) / 3

                                              = 0.59 atm

partial pressure of oxygen = ( 0.04 × 0.082 × 273 ) / 3

                                            = 0.29 atm

Thus, The partial pressure of nitrogen is 0.59 atm and the partial pressure of oxygen is 0.29 atm.

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O₂ (g) + 2 H₂ (g) → 2 H₂O (g) + Energy ,  this is exothermic process.

An exothermic process releases heat and raises the temperature of adjacent areas. Endothermic processes absorb heat and cool the environment.

A chemical reaction or physical change is endothermic when a system absorbs heat from the environment. During endothermic processes, the system gains heat from the environment, resulting in a decrease in the temperature of the environment.

In thermochemistry, an endothermic process is a thermodynamic process accompanied by an increase in the enthalpy H of the system. In such processes, closed systems typically absorb thermal energy from the surroundings and transfer heat to the system.

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3-bromo-2-chlorobenzaldehyde

on the 3 carbon you have bromine, 2 carbon you have chlorine, and on the 1 carbon you have an aldehyde

3-bromopropanal

on the 3 carbon you have a bromine,since there are 3 carbons it's propane but one carbon is an aldehyde so the suffix has to be -propanal

The concentration terms are molality, normality and mole fraction. Molarity can be used to find out the ionic strength of any solution. Therefore, the mass of barium chloride is 0.80g.

Molarity can be calculated by dividing number of moles of solute by volume of solution in liter. Molarity is affected by temperature. Its unit is mole/liter. It measure the concentration of any solute in a solution.

Mathematically,

Molarity= number of moles of solute÷ volume of solution in liter (1)

Where,

moles= given weight ÷ molecular weight

         = w÷ 208.23 g/mol

Substituting values in equation 1, we get

0.250 M =(w/ 208.23 )/(0.500 L)

w=26.0g

Therefore, the mass of barium chloride is 0.80g.

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