Which activity helps some animals maintain their body temperature?
A. Breathing in carbon dioxide
B. Making sugars
C. Rolling in mud
D. Running away from danger

From the calculations, the half life of the material is 6.5 days.

The term radioactivity has to do with the spontaneous disintegration of a specie.

Uisng the formula;

N=Noe^-kt

N= amount at time t = 0.135 Ci or 4.995 ×10^9 Bq

No = amount initially present =  1.75 x 10^12 Bq

k = rate constant = ?

t = time taken = 55 days

Hence;

4.995 ×10^9  = 1.75 x 10^12e^-55k

4.995 ×10^9/1.75 x 10^12 = e^-55k

2.85 * 10^-3 = e^-55k

ln2.85 * 10^-3 = -55k

k = ln2.85 * 10^-3/-55

k = 0.1066 day-1

Half life = 0.693/ 0.1066 day-1

= 6.5 days

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Answer: burning and digesting

Both of these are chemical changes.

Answer:

burning and digesting

Explanation:

Answer:

C.) trigonal pyramidal, polar

Explanation:

Around the phosphorus central atom, there are 3 fluorine atoms and 1 lone pair. This makes the shape tetrahedral, but gives it a trigonal pyramidal geometry. The lone pair on the phosphorus disrupts the balance of the molecule and pulls the electrons towards it. This makes the molecule polar.

From the mechanism shown, the major product of the reaction is (S)-(+)-2-octanol.

An SN2 reaction is one in which there is an inversion of configuration and the attack of the nucleophile occurs from behind the substrate.

As shown in the mechanism attached here, the major product of this reaction is (S)-(+)-2-octanol.

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Answer:

31°C

Explanation:

Using the ratio, we can find the temperature of the gas at 705mm.

 725mm : 32°C

 705mm : x

[ x is the temperature we have to find ]

Cross multiply the ratios.

 725x = 705 × 32

 725x = 22560

 x = [tex]\frac{22560}{725}[/tex] = 31°C

Answer: Products have a higher total potential energy than the reactants.

Explanation:

During endothermic reactions, energy is absorbed, meaning that the products will have more potential energy.

Answer: B. Grams liquid x mol/g x A Hvap

Stoichiometry used to calculate energy absorbed when a mass of liquid boils is Grams liquid × mol/g × ΔHvap.

It is the amount of heat evolved when mole of liquid is boiled to form vapours. It is a function of pressure according to which the change will happen in the reaction.

Given is that a particular mass of liquid is boiling.

We have supposed that heat of vapourisation for the same liquid is ΔHvap mol/g. Now if ΔHvap is the heat for 1 mole per gram of the liquid then if the mass of liquid is given,

Energy absorbed can be calculated as = Grams liquid × mol/g × ΔHvap

We should know that when a liquid boils it transforms into gaseous state and the process is called as Vapourisation.

Therefore, Stoichiometry used to calculate energy absorbed when a mass of liquid boils is Grams liquid × mol/g × ΔHvap.

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Answer:

O One system must have higher kinetic energy than the other system.

Explanation:

Higher KE of the system means hotter......the hotter will transfer heat to the cooler by conduction when they are in contact.

Answer:

carbonhydrates, fats and ptoteins

Answer:3 carbohydrates, fats, and proteins

Explanation:

.we can read the chemical preparation of the reaction as: "4 g of hydrogen react with 32 g of oxygen to give 36 g of water".   :)

Answer:

chemical formula of isopropyl alcohol can also be written as: C3H7OH, CH3CHOHCH3 or (CH3)2CHOH.

chemical formula of ethanoic acid is CH₃COOH.

Explanation:

1 moles Lead(II) Acetate to grams = 325.28804 grams

3.47 moles Lead(II) Acetate to grams = 325.28804 ×3.47 grams=1128.749 grams

1 moles sodium chloride to grams=58.5 grams

3.47 moles sodium chloride to grams=58.5×3.47 grams

=202.995 grams

Explanation:

 On the basis of electrical conductivity, materials are classified as conductors, semi-conductors and non-conductors. Conductors : Substances through which electricity can easily pass through are known as conductors. For example, copper, silver, mercury etc are good conductors of electricity

Answer:

dust form

Explanation:

because dust spreads alot faster

The pH of the buffer solution after the addition of sulfuric acid is determined as 4.43.

The initial moles of acid and base conjugate is determined as follows;

n = CV

na₁ = (150 x 1.1341)/1000

na₁ = 0.17 mol

nb₁ = (100 x 0.831)/1000

nb₁ = 0.083 mol

H₂SO4  ⇄ 2H²⁺  + SO₄²⁻

na₂ = (10 x 0.01)/1000

na₂ = 0.0001 mol

nb = 0.083 - 2(0.0001) = 0.0829 mol

na = 0.17 + 2(0.0001) = 0.1702 mol

[tex]Ka = \frac{[CH_3COO][H^+]}{[CH_3COOH]} \\\\1.8\times 10^{-5} = \frac{0.0829(H^+)}{0.1702} \\\\H^+ = \frac{(1.8 \times 10^{-5})(0.1702)}{0.0829} \\\\H^+ = 3.696 \times 10^{-5}\\\\pH = -Log [H^+]\\\\pH = -Log (3.696 \times 10^{-5})\\\\pH = 4.43[/tex]

Thus, the pH of the buffer solution after the addition of sulfuric acid is determined as 4.43.

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The number of atoms present in 0.58 mole of magnesium, Mg is 3.49×10²³ atoms

1 mole of Mg = 6.02×10²³ atoms

1 mole of Mg = 6.02×10²³ atoms

Therefore,

0.58 mole of Mg = 0.58 × 6.02×10²³

0.58 mole of Mg = 3.49×10²³ atoms

Thus, 3.49×10²³ atoms are present in 0.58 mole of Mg

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Answer:

3150.5g

Explanation:

1 mole of nitric acid weighs 63.01g

so i did 63.01g times 50.0g which equals 3150.5g

g= Grams

Hope This Helped

Answer:

0.79 moles

Explanation:

Formula :

Number of moles = Weight of substance / molecular mass

=============================================================

Here :

⇒ Weight of HNO₃ = 50 g

⇒ Molecular mass = 63 g

============================================================

Solving :

⇒ Number of moles = 50/63

⇒ Number of moles = 0.79 moles

Answer:

Explanation:

Answer:

It represents the number of atoms of that particular element present in the compound. In C₂H₄O₂ there are 2 Carbon atoms, 4 Hydrogen atoms and 2 Oxygen atoms.

Answer:

675g

Explanation:

The equation that relates mass, density and volume is:

Density = mass ÷ volume

By rearranging the equation we can find the mass of the cube.

Mass = density × volume

Mass = 45 × 15

∴ Mass = 675 grams

The combined reaction is exothermic , with the heat of reaction as -206.7 kJ

A reaction in which energy is liberated when reactants react to form products , The energy level of the reactant is more than that of the products.

The energy is liberated in the form of heat.

In the question it is given that

The energy changes in two partial reactions are 225.3 kJ and -432.0 kJ

The combined reaction is exothermic.

For the reaction to be exothermic the value of the heat of the reaction must be negative.

Summing the two energy changes will give us the heat of the combined reaction.

225.3 - 432.0

= -206.7 kJ

The combined reaction is exothermic , with the heat of reaction as -206.7 kJ.

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To give 33.6 dm³ hydrogen gas at STP, 18.06 x 10²³ atoms of Na must react completely.

A mole is a unit of measurement used to measure the amount of any fundamental entity (atoms, molecules, ions) present in the substance.

As according to the given equation, 2 moles (ie 12.04 x 10²³ atoms) of Na-atoms produces 1 mole (22.4 ltr) of H₂-gas.

Hence, to produce 33.6 ltr (equivalent to 33.6 dm³) of H₂-gas produced by ;

   = 12.04 x 10²³ atoms of Na / 22.4 ltr of H₂-gas x 33.6 ltr

   = 18.06 x 10²³ atoms of Na

Hence, To give 33.6 dm³ hydrogen gas at STP, 18.06 x 10²³ atoms of Na must react completely.

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The volume of titanium with mass of 0. 10g and density of 4. 51 g/cm³ is 0. 02 cm³

Volume is known to be equal to the mass divided by the density.

It is written thus:

Volume = Mass / density

The volume is calculated using the formula:

Volume = mass ÷ density

Given the mass = 0. 10g

Density = 4.51 g/cm³

Substitute the values into the formula

Volume of titanium = 0. 10 ÷ 4.51 = 0. 02 cm³

Thus, the volume of titanium with mass of 0. 10g and density of 4. 51 g/cm³ is 0. 02 cm³

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Answer:

B. Can only be concave

Explanation:

Statement A is false because lenses do not reflect light. Lenses do have an optical axis.

Answer:

synthesis reaction

Explanation:

please mark me as brainlest

Taking into account the definition of dilution, 227.5 mL of the 0.20 M solution is needed to prepare 455 mL of the diluted NaOH.

Dilution is the process of reducing the concentration of solute in solution, which is accomplished by simply adding more solvent to the solution at the same amount of solute.

In a dilution the amount of solute does not change, but as more solvent is added, the concentration of the solute decreases, as the volume (and weight) of the solution increases.

A dilution is mathematically expressed as:

Ci×Vi = Cf×Vf

where

In this case, you know:

Replacing in the definition of dilution:

0.20 M× Vi= 0.10 M× 455 mL

Solving:

(0.10 M× 455 mL)÷ 0.20 M= Vi

227.5 mL= Vi

In summary, 227.5 mL of the 0.20 M solution is needed to prepare 455 mL of the diluted NaOH.

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The organic product formed in the reaction shown in the image would be bromoethane.

Alkanes, such as ethane undergoes a substitution reaction with halogens such as bromine to produce haloethanes.

For example, the equation of the reaction between ethane and bromine water is as below:

[tex]C_2H_6 + Br_2 --- > C_2H_5Br + HBr[/tex]

The products formed are bromoethane and hydrobromic acid.

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Answer:

C

Explanation:

Recall that, at equilibrium, the concentration of the reactants and products stop changing because both the forward and reverse reaction rates are equal.

Therefore, Choice C is correct.

Choice A is incorrect because there is no indication that the upper line describes the products and the lower line describes the reactants.

Choice B is incorrect because the statement, while true, is not reflected by the graph. (The two lines after equilibrium are not at the same y-value.)

Choice D is incorrect because the forward reaction rate generally decreases as time increases due to the decrease in reactant concentration(s).

Answer:

H2 PO4 -1 is the correct answer

An acid and a base which differ from each other by a proton are said to form a conjugate pair. Here the conjugate base of H₃PO₄ is H₂PO₄⁻. The correct option is C.

The entity produced when acid gives up a proton has a tendency to regain the proton and hence it behaves as a base. It is called the conjugate base of the parent acid. A base is a substance which acts as a proton acceptor.

Here the conjugate base of H₃PO₄ is formed when a proton is lost from it. So the lose of one proton forms the molecule H₂PO₄⁻ which is the conjugate base. An acid is a proton donor.

When a base accepts a proton it has a tendency to donate the proton and hence behaves as an acid. It is called the conjugate acid of the parent base.

Thus the correct option is C.

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