Do all living things have cells?

Answer:

They use hypotheses to guess a result based on what they already know. Observations are used to record the results of an experiment. Predictions are used to have an expected outcome of a test, thinking the hypothesis is correct. Experiments are used to test the hypothesis.

Answer:

0.035 m CH3CH2CH2OH

Explanation:

We know that freezing point is a coligative property hence it depends on the number of solute particles present.

Covalent substances do not break up into ions, hence they do not produce many particles in solution unlike ionic substances. Hence, ionic substances have a far higher freezing point than covalent molecules.

For this reason, 0.035 m CH3CH2CH2OH has the lowest freezing point.

Answer:

d) BaF2

Explanation:

The compound which is more soluble in an acidic solution than in a neutral solution is shown below:-

First we will compare acidic with Neutral

[tex]acidic \rightarrow H+ ions[/tex]

So,

[tex]PbBr2 \rightarrow Pb+2 + 2Br-[/tex]

[tex]BaF2 \rightarrow Ba+2 + 2F-[/tex]

[tex]AgI \rightarrow Ag+ + I-[/tex]

[tex]CuCl \rightarrow Cu+ + Cl-[/tex]

Now, when we add H+ ions, so it will be

[tex]BaF2 \rightarrow Ba+2 + 2F-[/tex]

[tex]F- + H2O <-> HF + OH-[/tex]

Then it will reduces F-, as BaF2 begin to form more aqueous ions, so, it will rises the solubility

Answer:

four holes

Explanation:

A ball and stick model is a representation of a molecule that can show the number of bonds and sometimes, the stereochemistry of the molecule under study.

The number of holes on present in the ball and stick model for any atom corresponds to the number of bonds that particular atom can form without violating the octet rule.

Carbon is usually tetravalent, it forms four bonds to other atoms. Hence we expect carbon to have four holes.

Answer:

Explanation:

Carbon - Four-hole

Nitrogen - Three-hole

Oxygen - Two-hole

Hydrogyn - Two-hole

Answer:

Option B:

Electron capture is the combination of a core electron with a proton to yield a neutron within the nucleus.

Explanation:

The electron capture is a nuclear process whereby a neutral atom absorbs an electron from its closest shell (which is usually the K shell of the atom).

This capture phenomenon, causes one of the protons within the nucleus of the atom to convert into a neutron because of the merging of the positive and negative charges. Once they merge, a light particle called the electron neutrino is emitted from the nucleus of the atom.

This phenomenon occurs mostly in atoms that have a proton-rich nucleus. This provides the positive charge that pulls the electron from its shell into the nucleus of the atom.

Answer:

[tex]M=0.0256M[/tex]

Explanation:

Hello,

In this case, the undergoing chemical reaction is:

[tex]PbSO_4(aq)+2KCl(aq)\rightarrow PbCl_2(s)+K_2SO_4(aq)[/tex]

In such a way, since all the lead (II) is converted due to the excess of potassium chloride, the moles of lead (II) in the sample are computed from the mass of lead (II) sulfate:

[tex]n_{Pb^{2+}}=12.8gPbSO_4*\frac{1molPbSO_4}{303.3gPbSO_4} *\frac{1molPb^{2+}}{1molPbSO_4} \\\\n_{Pb^{2+}}=0.0422molPb^{2+}[/tex]

Thus, since volume of the solution is 1.65 due to the fact that the addition of the reactants is not enough to significantly modify the reaction's volume, the resulting molar concentration of the lead (II) ions is:

[tex]M=\frac{n_{Pb^{2+}}}{V}=\frac{0.0422molPb^{2+}}{1.65L}\\ \\M=0.0256M[/tex]

Regards.

Answer:

The correct answer is "C. Qc > Kc, the reaction proceeds from right to left to reach equilibrium"

Explanation:

The reaction quotient Qc is a measure of the relative amount of products and reactants present in a reaction at a given time.

Being:

aA + bB ⇔ cC + dD

where a, b, c and d are the stoichiometric coefficients of the balanced equation, the coefficient Q is calculated as:

[tex]Qc=\frac{[C]^{c}*[D]^{d} }{[A]^{a} *[B]^{b} }[/tex]

If Qc <Kc there is less concentration of products than in equilibrium, with which the reaction will evolve to the right to increase the concentration of products.  

If Qc> Kc, it is possible to affirm that the reaction will evolve to the left since in this case the direct reaction predominates and there will be more product present than what is obtained in equilibrium. Therefore, this product is used to promote the reverse reaction and achieve equilibrium. Then the system will evolve to the left to increase the concentration of reagents.

If Qc = Kc, it means that the reaction is in equilibrium.

In the case of the reaction:

2 SO₂ (g) + O₂ (g) ⇔ 2 SO₃(g)

the value of the constant Qc is calculated as:

[tex]Qc=\frac{[SO_{3} ]^{2} }{[SO_{2} ]^{2} *[O_{2} ]}[/tex]

Being:

and replacing:

[tex]Qc=\frac{10^{2} }{0.010^{2} *0.010}[/tex]

you get:

Qc=100,000,000=1*10⁸

Being Kc=4.3*10⁶, then Qc>Kc and the reaction proceeds from right to left to reach equilibrium.

So the correct answer is "C. Qc > Kc, the reaction proceeds from right to left to reach equilibrium"

Answer:

0.384928 J/g°C

Explanation:

The formula for Specific Heat (C)

= q/m × ∆t

Where q = Heat energy required to heat the compound (in joules)

m = mass of the compound (sample)

∆t = Change in temperature

In the question, we are given the following values.

m = 5.0g

∆t = Change in temperature = 75°C - 25°C

= 50°C

q = Heat energy = 23 cal

We have to convert to joules

One calorie is equal to 4.184 joules.

1 Cal = 4.184 joules

23 Cal =

23 × 4.184 joules

= 96.232 joules

Specific Heat (C) of copper

= 96.232 J /(5g × 50°C)

= 96.232J / 250

= 0.384928 J/g°C

Therefore, the Specific Heat of Copper is 0.384928 J/g°C

Answer:

C. Zero

Explanation:

A concentration cell is defined as a type of galvanic cell which has two equivalent half-cells of the same constituent in the electrodes but different concentration in the electrolytes.

For a concentration cell, the standard cell potential is always Zero and the cell potential is usually measured with the use of the Nernst equation.

Answer:

Explanation:

The definition of acids and bases by Arrhenius Theory  was modified and extended by  Bronsted-Lowry.

Bronsted-Lowry defined acid as a molecule or ion which donates a proton while a base is a molecule or ions that accepts the proton. This definition can be extended to include acid -base titrations in non-aqueous solutions.

In this theory, the reaction of an acid with a base constitutes a transfer of a proton from the acid to the base.

From the given information:

[tex]\mathsf{HCN _{(aq)} + H_2O_{(l)} \to CN^{-}_{(aq)} + H_3O_{(aq)}}[/tex]

From above:

We will see that HCN releases an H⁺ ion, thus it is a Bronsted-Lowry acid

[tex]H_2O[/tex] accepts the H⁺ ion ,thus it is a Bronsted-Lowry base.

The formula of the reactant that acts as a proton donor is HCN

The formula of the reactant that acts as a proton acceptor is H2O

Answer:

83 atoms

Explanation:

5*(1 fe + 2 S) + 6(2 C + 4H + 2O) + 2*2(1 Ca + 2 H + 1 P + 4 O) = 15 + 36 + 32 = 83 atoms

Answer:

Explanation:

According to Bronsted-Lowry acids or base theory ,  the reagent capable of giving hydrogen ion or proton  will be acid and that which accepts hydrogen ion or proton  will be base .

C₉H₇N + HNO₂   ⇄    C₉H₇NH⁺ + NO₂⁻

If K > 1 , reaction is proceeding from left to right .

Hence HNO₂ is giving H⁺ or proton and C₉H₇N is accepting proton to form

C₉H₇NH⁺ .  

Hence HNO₂ is bronsted acid and C₉H₇N is bronsted base .

B )

when K < 1 , reaction above proceeds from right to left . That means

C₉H₇NH⁺ is giving H⁺ so it is a bronsted acid and NO₂⁻ is accepting H⁺ so it is a bronsted base .

Hence ,  NO₂⁻ is a bronsted base and C₉H₇NH⁺ is a bronsted acid .

Answer:

14.0 g

Explanation:

Step 1: Given data

Volume of solution (%w/v): 255 mL

Weight/volume % of glucose (solute): 5.50% (m/v)

Step 2: Calculate the mass of glucose

We can calculate the mass of glucose using the following expression.

%w/v = mass of glucose / milliters of solution × 100%

mass of glucose = %w/v × milliters of solution / 100%

mass of glucose = 5.50% (m/v) × 255 mL / 100%

mass of glucose = 14.0 g

Answer:

3.13%

Explanation:

Step 1: Given data

Mass of sodium chloride (solute): 3.60 g

Volume of solution: 115 mL

Step 2: Calculate the weight/volume % of the  solute

We will use the following expression.

%w/v = mass of solute / milliliters of solution × 100%

%w/v = 3.60 g / 115 mL × 100%

%w/v = 3.13%

The weight/volume % of the  solute is 3.13%

Answer:

3.13

Explanation:

correct

Answer:

The correct option is H₂

Explanation:

An ideal gas is the gas that obeys the gas laws perfectly. There molecules occupy little/negligible space with no interaction. Since they occupy negligible space, it can be said that the smaller the molecule of a gas, the more it behaves like an ideal gas. There size also accounts for there weak intermolecular force between it's molecules.

From the explanation above, H₂ has the smallest molecule and hence will behave the most like an ideal gas.

The gases that one would expect to behave the most ideally even under extreme conditions is H2.

H2 is simply known as a molecule of hydrogen that has two hydrogen atoms which are bonded to each other by covalent bond.

Due to the fact that the hydrogen atom has a smaller size and lesser electronegativity the hydrogen molecule is thus regarded to be the least polar.

N2 is known to have greater polarizability than hydrogen molecule and thus cannot be the answer.

Note that for a gas to behave ideally, the attractive and repulsive intermolecular forces need to be negligible. When looking at the three molecules

H2,N2,CO, the molecule which is most polar will behave least ideally.

Therefore, hydrogen molecule will have the least intermolecular forces and will be most ideal.

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Answer:

pH of the buffer is 10.10

Explanation:

trimethylamine is a weak base that, in presence with its conjugate base, trimethylammonium ion, produce a buffer.

To determine the pH of the buffer we use H-H equation for weak bases:

pOH = pKb + log [Conjugate acid] / [Weak base]

pKb is -log Kb = 4.20

pOH = 4.20 + log [N(CH₃)₃] / [NH(CH₃)₃]

Replacing the concentrations of the problem:

pOH = 4.20 + log [0.20M] / [0.40M]

pOH = 3.90

As pH = 14 -pOH

Answer:

Scientific models are used to explain phenomena that can not be experience directly and it is also used for prediction.

Explanation:

An example of idea model is the Eistein equation.  An idea model shows how things interact together to produce a particular result.

An example of physical model is the solar system.

Computer model is used to predict long term events and an example of this is computer simulations.

Answer:

There will not be any ejection of photoelectrons

Explanation:

Energy of the photon= hc/λ

Where;

h= Plank's constant

c= speed of light

λ= wavelength of the incident photon

E= 6.6×10^-34 × 3 ×10^8/488 × 10^-9

E= 4.1 ×10^-19 J

Work function of the metal (Wo)= 2.9 eV × 1.6 × 10^-19 = 4.64 × 10^-19 J

There can only be ejected photoelectrons when E>Wo but in this case, E<Wo hence there will not be any ejection of photoelectrons.

Answer: 11.2 days

Explanation:

Expression for rate law for first order kinetics is given by:

[tex]t=\frac{2.303}{k}\log\frac{a}{a-x}[/tex]

where,

k = rate constant

t = age of sample

a = let initial amount of the reactant

a - x = amount left after decay process  

a) for completion of half life:

Half life is the amount of time taken by a radioactive material to decay to half of its original value.

[tex]t_{\frac{1}{2}}=\frac{0.693}{k}[/tex]

[tex]k=\frac{0.693}{5.6days}=0.124days^{-1}[/tex]

b) for completion of 75% of reaction

[tex]t=\frac{2.303}{0.124}\log\frac{100}{100-75}[/tex]

[tex]t=\frac{2.303}{0.124}\log\frac{100}{25}[/tex]

[tex]t=11.2days[/tex]

The time for which she has to perform the experiment is 11.2 days

Answer:

a. Tadpoles possess the tendency to grow more rapidly close to the cooling water released from the power plant as the temperature is greater in these waters, permitting them to acquire more nutrients. Thus, in the given case, the factor is the temperature of the system.  

b. In the given case, the factor is the catalyst, and in the given case enzymes are the biological catalyst. An enzyme increases the rate of the reaction as they lower the activation energy.  

c. In the given case, the factor is the enzyme, as the blood comprises an enzyme, peroxidase, which catalyzes the decomposition of hydrogen peroxide.  

Answer:

Yes.

Explanation:

Substances are made up of matter or matter are made up of tiny molecules or atoms that occur naturally or some are synthetic or man made.

All matter are made up of substances called elements and each elements have its own physical and chemical properties and cannot be broken easily by ordinary chemical reactions.

Of all the 118 elements only 92 occur naturally and 26 are man made or synthetic which are made in the laboratories.

Answer:

a. (lowest bp) CH3CH2CH3 < CH3OCH3 < CH3CH2OH (highest bp

Explanation:

CH3CH2OH is an alkanol. The intermolecular forces present within the molecules include dispersion forces, dipole-dipole attraction as well as hydrogen bonding which is the major intermolecular force of attraction present.

CH3OCH3 is an ether. The intermolecular forces present within the molecules are dispersion forces and dipole-dipole attraction.

CH3CH2CH3 is an alkane. The only intermolecular forces present is dispersion forces.

The order of increasing strength of these intermolecular forces is dispersion forces ,dipole-dipole forces<hydrogen bonding, the alkanol has the highest bioling point, followed by the ether and then the alkane with the lowest boiling point.

The ranking of the compounds in terms of increasing the boiling point is option a.

Ethanol i.e. (CH3-CH2-O-H) has three types of intermolecular interactions i.e. weak van der Waals interaction, dipole-dipole interaction, and strong intermolecular H-bonding interaction.

While on the other hand,  in dimethyl ether (CH3-O-CH3) have two types of interactions - weak van der Waals interaction, and dipole-dipole interaction.

In propane (CH3-CH2-CH3) has only weak van der Waals interaction.

So ethanol needed more energy to overcome this these interactions for the conversion to a liquid state to the gaseous state.

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Answer:

Decreasing pH decreases the solubility; increasing salinity increases the salinity.

Explanation:

Atmospheric carbon dioxide in seawater is involved in the following equilibria:

(i)   CO₂(g) ⇌ CO₂(aq)

(ii)  CO₂(aq) + H₂O ⇌ H₂CO₃(aq)  

(iii) H₂CO₃(aq) + H₂O(l) ⇌ H₃O⁺(aq) + HCO₃⁻(aq)  

(iv) HCO₃⁻(aq)+ H₂O(l) ⇌ H₃O⁺(aq) + CO₃²⁻(aq)

1. Effect of pH  

Decreasing pH increases [H₃O⁺].

According to Le Châtelier's Principle, the position of equilibrium of (iv) will be pushed to the left.  

This, in turn, pushes the positions of equilibrium of (iii), (ii), and (i) to the left.

The net effect is that CO₂ is pushed out of the solution and back into the atmosphere.

Thus, decreasing the pH decreases the solubility of atmospheric CO₂.

2. Effect of salinity

Salinity includes the measurement of all ions in seawater, not just Na⁺ and Cl⁻.

An important ion that contributes to salinity is Ca²⁺.

Ca²⁺ ions are involved in the equilibrium  

Ca²⁺(aq) + CO₃²⁻(aq) ⇌ CaCO₃(s).

Thus, increasing the salinity ([Ca²⁺]) removes CO₃²⁻ from the solution and pulls the position of equilibrium of (iv) to the right.

The effect goes back through the chain of equilibria.

The net result is that more atmospheric CO₂(g) dissolves in the seawater to replace the CO₃²⁻ that has been removed.

Increasing the salinity increases the solubility of atmospheric CO₂.

Answer:

I hope it will work dear,

Explanation:

by simple mathematical rule,

then we know at half life 50% decay occur hence we get

      2.  50% = T 1/2

solving the 2 equations by cross multiplication we will get,

  T 1/2= 7.96 hr

THANKS FOR ASKING QUESTION:

Answer:

It shouldn't, but it might there is a chance. Liquid doesn't really weigh that much but it still can add slight weight.

Explanation:

The chemical could maybe make the balancer move a bit. But not a lot.

Answer:

See explanation

Explanation:

In this case, we can start with the half-reactions. If the total reaction is:

[tex]Zn_(_s_)~+~Cu^2^+~_(_a_q_)~->~Cu_(_s_)~+~Zn^2^+_(_a_q_)[/tex]

If we split the reaction we will have:

Half-reaction 1:

[tex]Zn_(_s_)~->~Zn^2^+_(_a_q_)[/tex]

Half-reaction 2:

[tex]Cu^2^+~_(_a_q_)~->~Cu_(_s_)[/tex]

Now we can add the electrons, keeping in mind that we have to obtain zero charge in both sides of each half-reaction:

Half-reaction 1:

[tex]Zn_(_s_)~->~Zn^2^+_(_a_q_)~+~2e^-[/tex]

Half-reaction 2:

[tex]Cu^2^+~_(_a_q_)~+~2e^-~->~Cu_(_s_)[/tex]

With this in mind, we can solve the questions:

Which one loses electrons?

In half-reaction number 1 we have the electrons in the products side, therefore this half-reaction is the one that loses electrons.

Which one gains electrons

In half-reaction number 2 we have the electrons in the reagent side, therefore this half-reaction is the one that gains electrons.

Which one is oxidized?

If half-reaction number 1 loses electrons will be the oxidation reaction.

Which one is reduced?

If half-reaction number 2 gains electrons will be the reduction reaction.

Which species functions as the oxidizing agent in the following reduction-oxidation reaction?

If half-reaction number 2 is the reduction will be a oxidizing agent.

Which one the reducing agent?

If half-reaction number 1 is the oxidation will be a reducing agent.

I hope it helps!

Answer:

Have only single bonds.

Explanation:

Hello,

In this case, we need to remember that saturation is a state at which a carbon chain contains no insaturations, that is neither double nor triple bonds such case are alkenes and alkynes, but saturations only which are characterized by the presence of single bonds between adjacent carbon atoms. Such is the case of ethane (CH₃-CH₃), propane (CH₃-CH₂-CH₃), butane (CH₃-CH₂-CH₂-CH₃) and so on.

Best regards.

Answer:

Bohr's Atomic model

Explanation:

The limitations of Bohr’s model are Bohr’s model of an atom that could not explain the line spectra of atoms containing more than one electron called multi-electron atoms.

Answer:

i can't understand the question