please help
Why does a smoke detector use alpha radiation rather than beta or gamma radiation?

Answer:

(A) 0.80 M

(B) 0.64 g

(C) 0.050 M

(D) 1.6 M

Explanation:

(A)

Convert 4.0 g to moles with molar mass. Convert 125 mL to L.

4.0 g x (1 mol/39.998 g) = 0.100 mol

125 mL x (1 L/1000 mL) = 0.125 L

Molarity = mol/L

Molarity = 0.100 mol/0.125 L = 0.80 M

(B)

Find moles of NaOH with the molarity you just found. And convert 20 mL to L.

Molarity = mol/L

0.80 M = mol/0.020 L

mol = 0.016

Convert moles to grams with molar mass.

0.016 mol x (39.998 g/1 mol) = 0.64 g

(C)

You know the molarity of a NaOH solution (Part A). 30 mL initial volume and 480 mL final volume are given. Dilution question so use the dilution formula.

M1V1 = M2V2

(0.80 M)(30 mL) = (M2)(480 mL)

M2 = 0.050 M

(D)

Dilution question again, use the dilution formula.

M1V1 = M2V2

(0.80 M)(200 mL) = (M2)(100 mL)

M2 = 1.6 M

Answer:

I think B

Explanation:

Red litmus paper is used more to find bases, blue litmus paper changes better when coming to find acids. So I believe it is B

The best approach best investigate whether substances are basic is to test each substance with red litmus paper.

Basic compounds are those which have a pH value in between the range of 7.1 to 14.

Red litmus paper changes its color from red to blue when comes in the contact of basic compounds. So to check the basicity of household substance we should use red litmus paper.

Hence test each substance with red litmus paper.

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Water evaporates more slowly than alcohol because water has more surface tension and more cohesive force than alcohol, So it takes more time for water to evaporate than for alcohol.

In alcohol, only O-H present is hydrophilic i.e. polar. Apart from this alcohol has a large hydrocarbon group i.e. C-H present in it, which is non-polar in nature. As a result, the attractive force between the atoms in alcohol is less. As a result, during boiling, the bonds between the atoms vibrate and break quickly. So alcohol evaporates faster.

In water, the entire molecule is polar. So there exists a strong attractive force between them. So the cohesive force is more in the case of water as compared to that of alcohol. As water is boiled the O-H bonds start to vibrate, since the bond is stronger, it requires higher energy for boiling. Thus it evaporates slower.

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The concentration of calcium ion in the pill is 18,320 ppm.

To calculate the concentration of calcium ion in parts per million (ppm), we need to determine the mass of calcium ion in the pill and divide it by the mass of the pill, then multiply by 1,000,000.

Mass of the pill = 2.43 g

Mass of Ca^2+ = 44.6 mg = 0.0446 g

Now, we can calculate the concentration in ppm:

Concentration of Ca^2+ (ppm) = (Mass of Ca^2+ / Mass of the pill) * 1,000,000

Concentration of Ca^2+ (ppm) = (0.0446 g / 2.43 g) * 1,000,000

Concentration of Ca^2+ (ppm) ≈ 18,320 ppm

The concentration of calcium ion in the pill is approximately 18,320 ppm.

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The mass of the HCl that is required for the reaction is 2.92 g

The mass of the hydrogen gas produced is 0.08 g

Number of moles of the iron = 2.3 g/56 g/mol

= 0.04 moles

We have that 1 mole of the iron reacts with 2 moles of HCl

0.04 moles of iron would react with 0.04 * 2/1

= 0.08 moles

Mass of the HCl required = 0.08 moles * 36.5 g/mol

= 2.92 g

We have that the mole ratio of the iron and the hydrogen is 1:1 kit then follows that mass of the hydrogen produced would now be;

0.04 moles * 2 g/mol

= 0.08 g

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Answer:

The reaction is exothermic as the solution becomes warm.

Explanation:

Hello there!

In this case according to the described reaction between sodium metal and water, we can write up the chemical equation whereas the products turn out to be sodium hydroxide and hydrogen gas:

[tex]2Na+2H_2O\rightarrow 2NaOH+H_2[/tex]

Moreover, these reactions are known to be highly exothermic, for that reason the solution becomes warm as the reaction releases heat as it goes to completion.

Best regards!

The standard cell potential (E°cell) of the reaction is found to be + 0.38 V, hence, option A is correct.

We will be usig the equation,

E°cell = (ΔG° / -nF) standard Gibbs free energy change is ΔG°, number of electrons transferred in the balanced equation is n, and Faraday constant (96,500 C/mol) is F. In the given reaction, 3 electrons are transferred, so n = 3.

Given ΔG° = -110 kJ/mol and F = 96,500 C/mol, we can substitute these values into the equation to calculate E°cell,

E°cell = (-110,000 J/mol / (-3 * 96,500 C/mol))

E°cell = 0.38 V

Therefore, the answer is, a. + 0.38 V

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Answer:

Dilution is the process of decreasing the concentration of a solute in a solution, usually simply by mixing with more solvent like adding more water to the solution

Unicellular organisms such as amoeba and leishmania undergo binary fission.

Binary fission can be described as a form of asexual reproduction where an organism divides into two, each part having one copy of genetic material.

Binary fission can be described as a kind of asexual reproduction observed in prokaryotes and a few single-celled eukaryotes. In asexual reproduction, there is a separation of the parent cell into 2 new daughter cells. This process occurs with the division and duplication into two parts.

Binary fission is a primary of reproduction in prokaryotic organisms. Binary Fission happens without spindle apparatus formation in the cell.  The single DNA molecule starts replication and attaches each copy to parts of the cell membrane.

Prokaryotes and eukaryotes such as euglena reproduce via binary fission. This process is rapid, and its speed varies in species. The time needed by bacteria to double the cells it has is called known as doubling time.

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Answer:

habitat destruction, overexploitation, climate change, nitrogen pollution, and invasive species.

Explanation:

Main Modern Causes of Extinction:

habitat destruction - the process by which a natural habitat becomes incapable of supporting its native species.

overexploitation - harvesting a renewable resource to the point of diminishing returns.

climate change - includes both global warmings driven by human emissions of greenhouse gases and the resulting large-scale shifts in weather patterns.

nitrogen pollution - a form of water pollution, refers to contamination by excessive inputs of nutrients.

invasive species - an introduced organism that negatively alters its new environment.

Answer:

To make glue. aaaaaaaaa

Answer:

Cleaning

Explanation:

Hydrochloric acid is an ingredient in household cleaners because it helps clean tough stains.

Answer:

Percent volume-volume (%(v/v)) = 100 x (volume of solute / volume of solution)

Percent volume-volume (%(v/v)) = 100 x (volume of solute / volume of solution)ex. 20 ml of methanol dissolved in enough water to make 200 ml of solution would result in a 10 % methanol solution

Percent volume-volume (%(v/v)) = 100 x (volume of solute / volume of solution)ex. 20 ml of methanol dissolved in enough water to make 200 ml of solution would result in a 10 % methanol solution-the units may be any units of volume you chose - as long as they are consistent

Percent volume-volume (%(v/v)) = 100 x (volume of solute / volume of solution)ex. 20 ml of methanol dissolved in enough water to make 200 ml of solution would result in a 10 % methanol solution-the units may be any units of volume you chose - as long as they are consistent-this concentration unit is most often used when mixing two liquids

Answer:

True

Explanation:

DON'T GIVE BRAINLIEST TO THE FILE EXPLOITER!!!!

By dividing the concentration of the reference solution by 100, you will obtain the concentration of the desired solution, which is 100 times less concentrated than the reference solution.

To find the concentration of a solution that is 100 times less than another solution, you can follow these steps:

1. Determine the concentration of the reference solution. Let's denote it as [A]₀.

2. Calculate the concentration of the desired solution. Let's denote it as [A].

3. Since the desired solution is 100 times less concentrated than the reference solution, you can divide the concentration of the reference solution by 100 to obtain the concentration of the desired solution:

  [A] = [A]₀ / 100

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In the direct reaction HCO3- + H2O ⇌ CO32- + H3O+, HCO3- acts as a base.

H2PO4- and HPO42-

H3O+ and OH-

H2CO3 and CO32 are

What is conjugate acid?

An acid and a base which differ only by the presence or absence of a proton are called a conjugate acid-base pair.

Part A:

In the direct reaction HCO3- + H2O ⇌ CO32- + H3O+, HCO3- acts as a base. This is because it accepts a proton (H+) from water (H2O) to form H3O+ (a hydronium ion). In this reaction, HCO3- acts as a Bronsted-Lowry base.

Part B:

Conjugate acid/base pairs among the options are:

H2PO4- and HPO42- (acid/base conjugate pair)

H3O+ and OH- (acid/base conjugate pair)

HCl and Cl- (not a conjugate acid/base pair; both are ions but not related by proton transfer)

H2CO3 and CO32- (acid/base conjugate pair)

So the correct answers are:

H2PO4- and HPO42-

H3O+ and OH-

H2CO3 and CO32-

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In the given reaction, 4 moles of KO2 react to produce 3 moles of O2. Therefore, if 10.5 moles of carbon dioxide (CO2) are used at STP, an equal amount of oxygen (O2) is produced. Hence, 10.5 moles of O2 will be generated.

According to the balanced chemical equation, the reaction 4 KO2(s) + 2 CO2(g) → 2 K2CO3(s) + 3 O2(g) shows that for every 4 moles of KO2, 3 moles of O2 are produced. Therefore, the molar ratio between KO2 and O2 is 4:3.

Since 10.5 moles of CO2 are used, we can use the stoichiometry of the reaction to determine the amount of O2 produced. As the reaction equation does not involve CO2, the amount of CO2 used does not directly affect the production of O2. Thus, 10.5 moles of CO2 will yield an equal amount of O2, resulting in 10.5 moles of O2 being produced at STP.

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Answer:

The period number tells which is the highest energy level occupied by the electrons.

Explanation:

Answer:

for the first one we need the previous question to be able to answer it. for the second one density and temperature

Explanation:

The major E2 reaction product formed when (1R,2S,4S)-2-chloro-4-methyl-1-(propan-2-yl)cyclohexane reacts with hydroxide ion in DMSO is (1S,2R,4S)-2-methyl-1-(propan-2-yl)cyclohexene.

In an E2 (elimination) reaction, a hydrogen atom and a leaving group are removed from adjacent carbon atoms, resulting in the formation of a double bond. In this case, the leaving group is the chloride ion (Cl-) and the hydrogen atom is removed from the carbon adjacent to the chlorine atom.

The given starting compound, (1R,2S,4S)-2-chloro-4-methyl-1-(propan-2-yl)cyclohexane, has a chiral center at carbon 2, which is marked as (S). When the hydroxide ion (OH-) attacks the carbon adjacent to the chlorine atom, the chlorine leaves and a hydrogen from the adjacent carbon is also removed. The resulting product is (1S,2R,4S)-2-methyl-1-(propan-2-yl)cyclohexene.

It's important to note that the stereochemistry of the starting compound and the resulting product is represented by the (R) and (S) designations, indicating the arrangement of the substituents around the chiral carbon atoms.

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The delta H for the reaction can be calculated using average bond energies. Based on the provided table, the bond energies are as follows: C-C (839 kJ/mol), H-I (348 kJ/mol), C-I (299 kJ/mol), and C-H (240 kJ/mol). To determine the delta H, we need to subtract the sum of the bond energies broken from the sum of the bond energies formed.

In this case, the bonds broken are C-C and H-I, with energies of 839 kJ/mol and 348 kJ/mol respectively. The bonds formed are C-I and C-H, with energies of 299 kJ/mol and 240 kJ/mol respectively. Calculating the delta H: Delta H = (Energy of bonds broken) - (Energy of bonds formed) = (839 kJ/mol + 348 kJ/mol) - (299 kJ/mol + 240 kJ/mol) = 1187 kJ/mol - 539 kJ/mol = 648 kJ/mol. Therefore, the delta H for the reaction is +648 kJ/mol. Since none of the given options match this value exactly, it seems there may be an error in the options provided.

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Answer:

CH4 and O2

Explanation:

The reactants of a chemical reaction are those that are on the left side of the chemical equation. In this case, methane (CH4) and oxygen (O2) which are on the left side, are the reactants.

The balanced equation is 6 Pb(s) + 6 Cr2O72-(aq) + 42 H+(aq) → 12 Cr3+(aq) + 42 H2O(l) + 6 Pb2+(aq). 6 moles of Pb(s) are oxidized for every 6 moles of Cr2O72- consumed. If 5 moles of Cr2O72- are used, it will oxidize 5 moles of Pb(s).

First, we need to balance the two half-reactions. Let's start with the reduction half-reaction of Cr2O72-: Cr2O72-(aq) + 14 H+(aq) + 6 e- → 2 Cr3+(aq) + 7 H2O(l).  To balance the oxygen atoms, we add 7 H2O to the left side: Cr2O72-(aq) + 14 H+(aq) + 6 e- → 2 Cr3+(aq) + 7 H2O(l). Next, we balance the hydrogen atoms by adding 14 H+ to the right side:

Cr2O72-(aq) + 14 H+(aq) + 6 e- → 2 Cr3+(aq) + 7 H2O(l) + 14 H+(aq)

Now, let's balance the oxidation half-reaction of Pb: Pb(s) → Pb2+(aq) + 2 e-. The equation is already balanced. To combine the two half-reactions, we multiply the reduction half-reaction by 6 and the oxidation half-reaction by 6 to ensure that the electrons cancel out: 6 Cr2O72-(aq) + 42 H+(aq) + 36 e- → 12 Cr3+(aq) + 42 H2O(l) + 84 H+(aq). 6 Pb(s) → 6 Pb2+(aq) + 12 e-. Now, we can write the balanced equation: 6 Pb(s) + 6 Cr2O72-(aq) + 42 H+(aq) → 12 Cr3+(aq) + 42 H2O(l) + 6 Pb2+(aq).

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YESS It is true!!. In general, atoms are most stable, least reactive, when their outermost electron shell is full. Most of the elements important in biology need eight electrons in their outermost shell in order to be stable, and this rule of thumb is known as the octet rule.

Answer:

ions

Explanation:

Answer:

4- radioactive isotopes

Explanation:

I don't remember exactly but this question was on the regents

Uranium-238  is a non- fissile element. It is a radioactive isotope that can be best used to determine geological formations. Thus, option 4 is correct.

Radioactive isotopes are elements that have an unstable atomic nucleus and can undergo radioactive decay to produce new particles and energy. They have the same atomic number as that of their parent species.

Isobars are a substance that has atomic mass and do not include uranium. Nuclear fusion and fission are the processes of nuclear energy that combine or splits the unstable nucleus to form a new particle.

Therefore, option 4. Uranium-238 is a radioactive isotope.

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1) The boron atom has only one unpaired electron, making it paramagnetic.

2) Boron atom has one unpaired electron, making it paramagnetic.Iron atom has four unpaired electrons, making it paramagnetic.

1. Boron atom and unpaired electrons Boron is a chemical element with the symbol B and atomic number 5. It is a trivalent metalloid and has three valence electrons. The electron configuration of boron is 1s² 2s² 2p¹. Therefore, the boron atom has only one unpaired electron, making it paramagnetic.2. Iron atom and unpaired electronsIron is a chemical element with the symbol Fe and atomic number 26. It is a metal and has two valence electrons. The electron configuration of iron is [Ar] 3d⁶ 4s². Therefore, the iron atom has four unpaired electrons, making it paramagnetic. Answer:Boron atom has one unpaired electron, making it paramagnetic.Iron atom has four unpaired electrons, making it paramagnetic.

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Answer:

N with a charge of (-3) is nitride

Explanation:

Answer:

The answer is C

It's a model of Decomposition reaction