Pls help this is for my semester exam

This graph shows the melting and boiling points of the alkali metals. Think about Francium, do you think it would have a higher or lower melting/boiling
point than lithium? Why? Can you predict it from the data?

Shroud's vintage t=4.28×10 3yr If the cloth veil from a mummy has a 14C14C energy of 10.0 disintegrations for minute per kg of carbon in comparison to live things that experience

When a government is no longer in effective control, the third component necessary for a state to exist, state structures appear to fall apart. Diverse regions of the nation's borders may be affected by this at varying intensities.

t = k1 ln N 0N t t = - dfrac 1 1.21 times 10-4 text year 1 ln dfrac 9.7 16.3

t=1.21104 yr1 1 ln 16.39.7 t = 4.28times 103 textyr

t=4.28×10 3 yr

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The concentration of the HCl (aq) solution was at least 1.0 M.

The abundance of a constituent divided by the sum of the mixture's volumes is the definition of concentration in chemistry. There are several different categories of mathematical description: mass concentration, molar concentration, number concentration, and volume concentration

P = 0.095atm(corresponds to 0.20g of CaCO3

so,moles of CaCO3 =0.20g/100gmol⁻¹=0.002moles

moles of HCl =(molesₓCaCO3ₓ2)=0.002ₓ2

M=0.004/4ₓ100

Concentration of HCl=1M

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The Reaction energy change = -456 kJ releases most energy to the surroundings. Option A is correct here

In a chemical reaction, one or more substances—also known as reactants—are changed into one or more additional substances—also known as products. Chemical elements or chemical compounds make up substances.

Chemical reactions are the processes by which a substance or substances change chemically to create a new substance or substances with entirely new attributes. The most energy is released into the environment via the reaction energy change, which is -456 kJ.

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The compounds in each of the following groups in order of increasing acidity or basicity, as indicated are basicity: Mg(OH)2,NaOH and Si(OH)4.

The base MgOH are more weaker as compared to that of the NaOH as these are really less in electronic configuration and has the lowest electrons in NaOH is eventually more stronger than all bases as it has the best conjugation basics property that defines the basic structure and strength.

The NaOH is stronger among all as it is having higher basic properties that's fir the basicity of any base. The Si(OH)4 are the basic that has the lesser basic properties than that of the NaOH and MgOH.

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Answer:

Photosynthesis would happen in the plant, while cellular respiration would happen in the plant and the fish. In the plant, photosynthesis occurs when light energy is converted into chemical energy used for growth and development. In fish, cellular respiration occurs when the fish takes in oxygen from the water and uses it to convert energy from food into usable energy...

Explanation:

When a food is burned, all the minerals are found in the ash. Therefore, the correct option is option A which  accurately describes minerals among all the given options.

A mineral is unique from its synthetic analogues, which must be generated through natural processes by definition. Artificial minerals, such as emeralds, diamond, sapphires, and other expensive gemstones, are routinely made in industry and scientific facilities and are frequently almost similar to their biological counterparts.

There are thousands of known mineral species, with around 100 of them constituting the primary dissolved minerals of rocks; they are known as rock-forming minerals. When a food is burned, all the minerals are found in the ash.

Therefore, the correct option is option A.

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The name of the compound (CH3CH2)2COHCH3 is butane-2,3-diol.

The compound is an alcohol, which means it contains a hydroxyl (-OH) group. The prefix "butane-" indicates that it has four carbon atoms in a straight chain, and the suffix "-diol" indicates that it contains two hydroxyl groups. The prefix "2,3-" specifies the positions of the hydroxyl groups on the carbon chain.

Butane-2,3-diol is also known by other names, including 2,3-butanediol, 2,3-dihydroxybutane, and 1,4-butanediol. It is a colorless, viscous liquid that is used in the production of plastics, solvents, and other chemicals.

The name of (CH3CH2)2COHCH3​ compound is butane- 2,3- diol.

The organic substance 2,3-butanediol has the formula (CH3CHOH)2. It falls under the vic-diol category. It exists as a chiral pair, three stereoisomers, and a meso isomer. All liquids are colorless. Precursors for various polymers and insecticides are examples of applications.

A butanediol with hydroxylation at C-2 and C-3 is known as butane-2,3-diol. It is a secondary alcohol, a glycol, and a butanediol.

Among its many possible uses are the production of printing inks, perfumes, synthetic rubber, fumigants, antifreeze agents, fuel additives, foodstuffs, and pharmaceuticals. 2,3-Butanediol (2,3-BD) is a promising bulk chemical.

Alcohols classified as primary have just one alkyl group on which the carbon atom of the hydroxyl group (OH) is connected. These major alcohols include, for instance, ethanol, methanol (propanol),

Thus, The name of (CH3CH2)2COHCH3​ compound is butane- 2,3- diol.

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Answer:

it act has a catalyst

Explanation:

sulphuric acid is a catalyst that is used in the preparation of chrom alum

Answer:

You could calculate the answer given the formula

M = mol/L

you can get mol using g/MolarMass

=> 42g/22.99g/mol = 1.82688125mol

1.25M = 1.82688125mol/V

=> apply simple algebra
V = 1.4615 L
=> Notice that the answer requires the unit to be ml
V = 1.4615L * 1000ml/L = 1461.5ml

=> Notice that the given grams have 2 sig figs

V = 1500 ml

1)Unlike other macromolecules, lipids can survive in rock records for millions or billions of years. This is typically used for rock quantification.

2)RNA is both a nucleotide acid and a prospective catalyst.

Macromolecules are largely polymers, which are long chains of molecular divisions known as monomers. Long polymers are found in carbohydrates, proteins, and nucleic acids. They are classified as macromolecules due to one‘s polymeric nature as well as large size. Macromolecules are massive molecules that populate cells and provide vital functions for life. Macromolecules, for example, offer structural support, a source of non - renewable power, the ability to store and collect genetic information, and the capacity to accelerate biochemical reactions. Lipids are fatty substances that serve numerous functions in your body. They are part of your cell membranes and help control what enters and exits your cells.

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Alkyl halides are produced by adding HBr to alkenes.The pi bond of the alkene functions as a weak nucleophile & reacts with electrophilic proton of HBr, which is a helpful way to conceptualize the reaction.

A 3-membered ring intermediate is produced as a result of the alkene acting as a nucleophile in this reaction and attacking the electrophilic bromine.The carbon that is most capable of stabilizing positive charge then is attacked from of the back side [akin to a backside attack inside the SN2 Mechanism] to produce the trans product.

The free-radical mechanism governs the addition reaction with HBr to an asymmetrical alkene inside the presence of peroxide.Here, an alkene interacts with a bromine radical to make an anti-Markovnikov product.

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Molecule move quickly at high temperatures & low pressures. These intermolecular attractive forces diminish as a consequence, and the real gas starts to behave like that of an ideal gas.

Many gases, including gas, oxygen, hydrogen, noble metals, some denser hydrocarbons like atmospheric co2, and combinations like air, can be classified as ideal gases if certain parameters are kept within reasonable bounds over a wide range of temperatures and pressures.

Whenever the pressure is expressed in kPa, the real gases standard is found to be 8.314J/Kmol. The pressure, quantity, temperature, & number of molecules of an ideal gas are all related by a single equation known as the ideal gas law.

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The energy level of the products is lower than the energy level of the reactants, and energy is released throughout the reaction. (Option A)

Chemical processes known as exothermic reactions generate heat. When heat is transferred from the system to its surroundings, as described, the heat flow q is considered negative. Therefore, the H of reaction is negative for exothermic reaction processes.

Therefore, a reaction is exothermic and its enthalpy will be negative if it releases more energy than it takes in. Consider this as a certain quantity of heat evaporating from (or being removed from) the reaction. Endothermic reactions have positive enthalpies because they absorb or use more energy than they produce.

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While tumor marker test results can be useful, they are not conclusive. A low result does not imply that you do not have cancer or that you are in remission.

CA 15-3, for example, is raised in less than half of patients with early breast cancer and in more than 80% of those with metastatic breast cancer. Three tumor markers, cancer antigen 15-3 (CA 15-3), cancer antigen 27.29 (CA 27.29), and carcinoembryonic antigen (CEA), have been used in breast cancer care to help monitor metastatic breast cancer (advanced disease), but they have not been found to be useful in detecting a breast cancer recurrence or extending lives. If the level falls, the treatment is effective. If it rises, the cancer may be spreading.

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The green bottom curve represents the catalysed reaction.

It is common practise to use catalysed reactions to quicken a particular chemistry's progress. The catalyst's main function is to offer the reaction a different, lower-energy pathway.

In a catalysed reaction, the reactant molecules readily pass the activation energy barrier and produce products. As a result, the activation energy of an uncatalyzed reaction is higher than the activation energy of a catalysed reaction.

For catalyzed reaction activation energy lower than uncatalyzed reaction. The complexity of the collisions necessary to reach a transition state means that without the catalyst, the Ce4+ ions and Tl+ ions must directly react in a termolecular reaction, which will be substantially slower.

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Answer:

When copper is heated in an atmosphere of hydrogen, the hydrogen gas can react with the oxygen present on the surface of the copper to form water. This reaction is known as reduction. The equation for this reaction is:

2H2 + O2 → 2H2O

In this reaction, the oxygen atoms in the copper are reduced (i.e., they gain electrons) and the hydrogen atoms are oxidized (i.e., they lose electrons). As a result, the oxygen is removed from the surface of the copper, leaving it oxygen-free.

This process is often used to purify copper and remove impurities, such as oxygen, that may be present on the surface of the metal. It is also used to produce high-purity copper for use in electrical and electronic applications, where the presence of oxygen can affect the conductivity of the metal.

Lattice structures: The correct answer is 2 anions and 3 cations. The unit cell contains a net 2 anions and 3 cations

What are lattice structures?

A lattice structure is a unit cell that fills all available space and may be tessellated along any axis without any spaces between the cells. These structures are a new development in terms of weight, energy, and time savings in modern manufacturing.

Anions are present at 8 corners and in one corner contribution is 1/8

so for 8 corners =(1/8)×8=1

And one anion i at centre and its contribution is one

total anion=2

Cations are present at 6 corners and contribution of one face is 1/2

So, net number of cations is 6×1/2 = 3 cations.

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The unit cell contains a net 3 cations and 2 anions.

Lattice structures: what are they?

A unit cell that completely occupies its area and can be tessellated along any axis without any gaps between the cells is known as a lattice structure. In terms of weight, energy, and time savings in modern manufacturing, these structures represent a new advance.

Corner atoms are counted as 1/8 of a total atom (just 1/8 of them are inside the unit cell's boundaries).

Atoms in the center count as one whole (whole thing inside the unit cell)

Face atoms are counted as one-half of a unit cell (half inside, half outside).

Therefore, the computation for anions is

1/8 anion at each corner x 8 corners on a cube = 1 anion

+ 1 whole anion

 = 2 anions per cell

The formula for cations is

1/2 cation at each face x 6 faces on a cube = 3 cations per cell

The unit cell contains a net 3 cations and 2 anions.

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For a first reaction its exothermic reaction ,increases, decreases.

For second reaction its exothermic reaction, increases, decreases.

For third reaction its endothermic reaction , increases, decreases.

What principle underlies Le Chatelier?

Le Chatelier's principles, sometimes known as the equilibrium law, allow for the prediction of a system in chemical equilibrium (such as the change in temperature or pressure).

The equilibrium position moves to the right at low temperatures.

Please see the accompanying file for a more thorough explanation.

CoCl₄²⁻ (aq)  ⇆ Co²⁺ + 4Cl⁻

1. Exothermic -

At low temp, the position of equilibrium shifts to right side and forms more pink color.

when the temp decreases. the K increases

[tex]K = \frac{[Co^{2+} ][Clx^{-} ]^{4} }{CoCl_{4} ^{2-} }[/tex]

2. At low temperature, more Co²⁺ produces and K values will increase as equilibrium shifts towards right.

Higher [Co²⁺] = Hugh K value

3. When temperature decreases the concentration of CoCl₄²⁻ decreases.

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After solving the equation the volume of the sample is 121.967L.

What is ideal gas equation?

The Ideal Gas Law (also known as the General Gas Equation) states that the pressure, volume, and temperature of an ideal gas are related through the equation PV = nRT, where P is the pressure, V is the volume, n is the number of moles of the gas, R is the ideal gas constant, and T is the absolute temperature. This equation is useful for understanding the behavior of gases and for calculating the amount of gas present in a given volume at a given temperature and pressure.

Using ideal gas equation

PV=nRT

V=nRT/P

n=59.9/44 =1.361 mol

V=[ 1.361×62.3636LmmHg/Kmol×293.15K]÷ 204 mm hg

=121.967L

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The volume of the sample is 121.967L.

Define the ideal gas law.

The ideal gas law, also known as the perfect gas law, is a relationship between a gas's pressure P, volume V, and temperature T in the range of low pressures and high temperatures where the gas's molecules move virtually independently of one another.

The ideal gas law (PV = nRT) connects the macroscopic characteristics of ideal gases. An ideal gas is one in which the particles are both non-repellent and non-attractive to one another (have no volume).

Using ideal gas equation

PV= nRT

V= nRT/P

n= 59.9/44 =1.361 mol

V=[ 1.361×62.3636LmmHg/Kmol×293.15K]÷ 204 mm hg

=121.967L

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The largest percent composition by mass of carbon is d)CH₄ .So,correct option is d.

We need to calculate the molecular mass of each of the compound and then check how much by mass carbon is present in the compound.

a)Molecular mass of calcium carbonate (CaCO₃) is =40+12+3ˣ16=100g

Now,we know that carbon has molecular mass=12g

So,percentage composition of carbon in CaCO₃=(12/100)ˣ100=12%

b)Similarly,molecular mass of carbon dioxide (CO₂)=44g

So,percentage composition of carbon in carbon dioxide is =(12/44)ˣ100=27.27%

c)Molecular mass of Sodium bicarbonate(NaHCO₃)=23+1+12+3ˣ16=84g

So,percentage composition of carbon in NaHCO₃=(12/84)ˣ100=12.85%

d)Molecular mass of methane(CH₄)=12+4ˣ1=16g

So, percentage composition of carbon in methane=(12/16)ˣ100=75%

We can see that by mass largest amount of carbon is present in methane(CH₄).

Hence,correct option is d.

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(Complete question) is:

Which of the following has the largest percent by mass of carbon?

a)CaCO₃

b)CO₂

c)NaHCO₃

d)CH₄

For the given question, statements A and B are true. So, Option E is correct as the work done given is negative.

According to the First Law of Thermodynamics, energy can only be changed from one form to another through the interplay of heat, work, and internal energy. Under no circumstances can energy be created or destroyed. It can be represented as:

ΔU = q + w

where,

ΔU = Total internal energy of the system

q = the heat that is transferred from a system to its surroundings

w = work done on the system or by the system

It is given in the question that q = 25 kJ and w = -15 KJ

So we get from the above equation-

ΔU = 25 - 15 = 10 KJ

The negative amount of heat that the environment has absorbed will be the value of internal energy.

Thus, the negative sign of work done shows that the work is done by the system on the surroundings while increasing the temperature of the surroundings.

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The slope of a distance-time graph for this motion will have a straight line to represent that the object in motion is at a constant speed.

A distance-time graph depicts how far an object has traveled in a specified amount of time. It is a simple line graph that depicts distance versus time findings. The Y-axis represents distance. On the X-axis, time is plotted.

The slope of the distance-time graph should always be constant because the bike is moving at a constant speed. As a result, the graph will be a straight line through the origin.

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The first and third statements are correct, impossible for every atoms in xef to satisfy this same octet rule.

What is octet rule?

The octet rule is a general chemical principle that represents the idea that main-group elements have a propensity to connect in a way that each atom has eight electrons in its valence shell, giving it the same electronic configuration as a noble gas.

TRUE

The octet rule is not followed by Xe. In fact, it creates ties. It can accommodate more than 8 electrons.

Since Xenon has valence electrons at the fourth energy level, it can reach the fourth sublevel, which gives it access to more than eight electrons. The Xenon is surrounded by 3 lone pairs and 2 bonded pairs of valence electrons in XeF2, which is dsp3 hybridised. The VSEPR forecasts the form to be linear.

The d sublevel is not accessible to elements in the first two periods of the Periodic Table, and they are instead required to abide by the octet rule (or duet H and He rule).

False. (b)

Due to its electrical arrangement of 1s2, 2s2, and 2p4, oxygen is tiny and does not have a vacant d-orbital.

(c) TRUE

Stronger bonds result from stronger bond orders. The bond strength will also be lesser the longer the bond is. One can tell that the NO+ bond will be stronger if they compute the bond order, which is greater for NO+ and the bond length, which is greater for NO-.

D. FALSE

Due to Covalency, the three oxygen forms are bonded. The double bond and single bond will switch places if you design a resonant structure, but in reality, no resonating form can fully explain the structure of ozone; the behaviour of the bond is the average of a single bond and a double bond between the oxygen atoms. There is neither a weaker nor a stronger bond in ozone because both bonds are equivalent.

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3.6 atm is the pressure inside the container after 243 mg of magnesium has reacted.

Pressure is defined as the force applied perpendicularly to an object's surface divided by the area over which that force is applied.

The reaction given is: Mg(s) + 2HCl(aq) → MgCl2(s) + H2(g). The moles of H2 gas formed are therefore equal to the moles of Mg that reacted, and can be calculated from: n = 0.243 g/(24.3 g/mol) = 0.01 moles (converting 243 mg to 0.243 g).

The added pressure is calculated by P = nRT/V using approximations: 0.08 L atm/molK for R (0.0821 rounded), 300K for T (303.15 before rounding) and 0.10 L for V.

Solving gives pressure = 2.4 atm. Finally, this number must be added to the initial pressure: 2.4 + 1.2 = 3.6 atm.

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The temperatures shown to the nearest 0.5°C is 42.5°C.

°C (Celsius):

Hence, as per the given image the temperatures shown to the nearest 0.5°C is 42.5°C.

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The radioactivity A of a drop of iodine I-131 if the mass of the drop is 1.5 g and the period is 13h is:  1.29 x 10^(-11) disintegrations/second.

Generally, To find the radioactivity of a drop of iodine I-131, you will need to use the following formula:

A = (N/M) * ln(2) / T

where:

To use this formula, you will need to know the atomic mass of I-131, which is about 130.906 amu, and its half-life, which is about 8.04 days. You will also need to convert the mass of the drop from grams to atomic mass units, which can be done by dividing the mass by the atomic mass of carbon-12 (12 amu).

First, convert the period from hours to seconds:

13 hours = 13 * 60 minutes/hour * 60 seconds/minute

= 5,040 seconds

Then, convert the period from seconds to days:

5,040 seconds = 5,040 seconds / (24 hours/day * 60 minutes/hour * 60 seconds/minute)

= 0.6 days

Then, calculate the half-life in seconds:

8.04 days = 8.04 days * 24 hours/day * 60 minutes/hour * 60 seconds/minute

= 691,840 seconds

Then, use the formula above to calculate the radioactivity:

A = (N/M) * ln(2) / T = (N/130.906 amu) * ln(2) / (691,840 seconds)

= (1.5 g / 12 amu) * ln(2) / (691,840 seconds)

= 0.125 * ln(2) / (691,840 seconds)

= 0.08867 * (1/691,840 seconds)

= 1.29 x 10^(-11) disintegrations/second

So the radioactivity of the drop of iodine I-131 is approximately 1.29 x 10^(-11) disintegrations/second.

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H will have the longest wavelength emission line for the transition between the n initial = 2 and n final = 1 levels.

A movement (or leap) of an electron from one energy level to another within an atom or artificial atom is referred to as an atomic electron transition. It seems discontinuous because the electron "jumps" from one quantized energy level to another in a matter of nanoseconds or less.

Electronic transitions occur in atoms and molecules as a result of electromagnetic radiation absorption or emission (typically UV or visible). Planck's equation, E = h, relates the energy change associated with a transition to the frequency of an electromagnetic wave. Transitions between these permitted orbits occur in photon absorption or emission. A photon is released when an electron transitions from a higher-energy orbit to a more stable orbit.

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All transporters were reduced as cytochrome oxidation is inhibited by cyanide. Since there is no terminating electron acceptor when O2 is absent, all carriers undergo reduction.

A negative charges particle known as an electron can be either independent or attached to an atom (not bound). Another of the three main types of elements within an atom is an electrode that is bonded to it; the other couple are protons & neutrons.

An electron's energy is determined by where it is in relation to the atom's nucleus. The distance an electron inside an atom has to travel from the nucleus depends on its energy level.

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Helium in 1 atm + 273 K, neon at 1 atm, neon at 2 atm, neon at 2 atm, and neon at 73 K

Advertising signs are the main application for neon gas. High voltage indicators are also made of neon, and helium-neon lasers are created by combining neon with helium. As a cryogenic refrigerant, liquid neon is employed.

Neon is extremely volatile and doesn't form any compounds that would allow it to be fixed to solids, which accounts for its relative paucity on Earth as well as the inner (terrestrial) planets. As a result, in the early Solar System, it broke free from the planetesimals while being warmed by the newly ignited Sun.

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The bonds ionic and covalent are in the NH4Cl as it has the one ionic bond and 3 covalent bonds.

There is definitely a coordinate bond (that's definitely a type of covalent bond wherein handiest one of the collaborating atoms donate each in their electrons to shape a covalent bond) among lone pair of nitrogen in ammonia(NH3) and a proton(H+ ion),which as a result creates an ammonium ion(NH4+).

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