The two elements that are frequently used for making transistors are
A. boron and aluminium
B. silicon and germanium
C. iridium and tungsten
D. niobium and columbium

Answer:

10.8 days (3 sig.figs.)

Explanation:

All radioactive decay is 1st order decay defined by the expression A = A₀e^-kt

which is solved for time of decay (t) => t = ln(A/A₀) / -k

A = final weight = 1.0 gram

A₀ = initial weight = 16.0 grams

k = rate constant = 0.693/t(1/2) = 0.693/2.69 days = 0.258 days⁻¹

t = ln(1/16) / -0.258da⁻¹ = (-2.77/-0.258) days = 10.74646792 days (calculator)

≅ 10 days (1 sig. fig. based on given 1 gram mass)

Answer:

Term

Liquid    C) takes the shape and volume of an entire container

Plasma    A) charged particles that do not have a definite shape or volume

Solid    B) has a fixed volume and shape

Gas    D) assumes the shape of the part of the container from the bottom up

The supplied statement indicates that the compound's molecular formula is (CH)ₙ = CH₆ = C₆H₆

Fuel cells may produce energy, power, and heat using hydrogen. The two industries where hydrogen is now most widely employed are urea manufacturing and petroleum refining, with the developing markets of utilities and transportation.

The lowest half figure ratio of a compound is revealed by the empirical formula for that molecule.

Empirical weight formula: 12 + 1 Equals 13.

Molecular weight = 78

n = Molecular weight/Empirical formula weight

n = 78.12/13

n = 6.00

Molecular formula = (CH)ₙ = CH₆ = C₆H₆

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Answer:

Bacteria decompose rotting plant animal material.

Explanation:

Theres good bacteria, and theres bad bacteria. some helps, and some makes things worse. so really, in some sense all of the above.

Hope that helps.

Bacteria are necessary for life because they help produce oxygen for plants and animals. Similarly bacteria decompose rotting plant and animal materials.

Bacteria are a type of organism which are classified as a kingdom of life. Bacteria are prokaryotic microbes that can spread diseases in animals and plants.

Some of the bacteria are very useful in for our life. Some of them are autotrophs thus, produce energy and oxygen. For example cyanobacteria release oxygen which is used animals and plants to respire.

Bacteria are very essential to degrade wastes and remove them from the  surface. They consume the decomposing plants and animals and make them biodegradable. Some bacteria living in plants helps in nitrogen cycle as well.

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Answer:

A.) They would have to prey on other organisms

Explanation:

The answers are.....

Animals that prey on rabbits would begin to prey on other organisms.

And...

Animals that prey on rabbits would starve.

And...

Animals that prey on rabbits would leave the area in search of more rabbits.

My son attends K12 and had this question on his unit 5 test. These were his answer choices and they were correct.

Answer:

An ion is an atom or group of atoms with a positive or negative charge. Ions form when atoms lose or gain electrons to obtain a full outer shell: For elements in groups 1, 2 and 3, the number of electrons lost is the same as the group number.

Explanation:

If an atom loses or gets electrons, it transforms into a charged particle known as an ion. An ion has a charge equal to the sum of its protons' and electrons' charges.

Electrons is defined as the smallest and negatively charged among the atom's constituent particles. The charge  moves from the positive terminal to the negative terminal as a result of the "electrical pressure" brought on by the voltage differential between the positive and negative terminals of a battery.

Depending on whether the number of electrons in an atom is greater or less than the number of protons in the atom, an atom can develop a positive charge or a negative charge. An atom is referred to as an ion when it is drawn to another atom due to an imbalance in its electron and proton numbers.

Thus, if an atom loses or gets electrons, it transforms into a charged particle known as an ion. An ion has a charge equal to the sum of its protons' and electrons' charges.

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Answer:

Liquid from a solid

Explanation:

Answer:

The correct answer is - 25.

Explanation:

Given:

Sum of the 3 consecutive odd numbers = 69

solution:

Let’s assume the initial number - 2X+1

Let's say the second number is -‘2X+3’ and

Let's say the largest number is- ‘2X+5’.

Sum of the numbers = 69

(2X+1) + (2X+3) + (2X+5) = 69

6X+9 = 69

6X = 69–9

6X = 60

X = 60/6

X= 10

So, x value would be 10. Putting value of X in 2X+5

= 2(10)+5

=25

= 25 (Answer)

Answer:

1) 33

2)47

3)33

Explanation:

The atomic number 33 is the same for both protrons and electrons.

Answer:

Ammonium dichromate is an inorganic compound with the formula (NH4)2Cr2O7. In this compound, as in all chromates and dichromates, chromium is in a +6 oxidation state, commonly known as hexavalent chromium. It is a salt consisting of ammonium ions and dichromate ions.

The rate constant at 65 C is k65= 4.8 x 10^-5 s^-1 .Below is the explanation for the answer

To find the rate constant at a different temperature, you can use the Arrhenius equation, which relates the rate constant to the activation energy and the temperature. The equation is:

k = A * e^(-Ea/RT)

where
k is the rate constant,
A is the pre-exponential factor (also known as the frequency factor),
Ea is the activation energy,
R is the universal gas constant,
T is the absolute temperature.

We are given that the activation energy is 83.5 kJ/mol and the rate constant at 45 C is 3.54 x 10^-5 s^-1. To find the rate constant at 65 C, we can substitute these values into the equation and solve for k.

k = A * e^(-Ea/RT)
k = 3.54 x 10^-5 s^-1 * e^(-(83.5 kJ/mol) / (8.314 J/mol*K * (45 + 273.15 K))

However, A is a constant that we don't know. To find the rate constant at 65 C, we can use the fact that the rate constant is proportional to the temperature. Therefore, we can find the ratio of the rate constants at 65 C and 45 C, then multiply it by the rate constant at 45 C to find the rate constant at 65 C.

k65/k45 = (T2/T1)^n
where
k65 is the rate constant at 65 C
k45 is the rate constant at 45 C
T2 is the temperature in Kelvin (65 + 273.15)
T1 is the temperature in Kelvin (45 + 273.15)
n is the order of the reaction, which is 1 in this case

we can find the rate constant at 65 C is:
k65 = k45 (T2/T1)^n
k65 = 3.54 x 10^-5 s^-1 * ( (65 + 273.15) / (45 + 273.15) )^1

k65= 4.8 x 10^-5 s^-1

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Answer:

T = 3.75 K

Explanation:

As we know

PV = nRT

R =8.3144598 J. mol-1. K-1

P = 0.562 atm

V = 83.3 mL

moles in 0.392 g of I2 = 0.392/mass of I2 = 0.392 grams/253.8089 g/mol = 0.0015 moles

Substituting the given values, we get

0.562 atm * 83.3 *10^-3 L = 0.0015 moles * 8.3144598 J. mol-1. K-1 * T

T = 3.75 K

The goal of the light reaction is to make NADH an high energy electron transporter and ATP an energy storing molecule.

The energy storage molecule ATP and the reduced electron carrier NADPH are produced by the light-dependent processes using light energy, which is required for the subsequent stage of photosynthesis. Light reactions in plants occur in the thylakoid membranes of organelles referred to as chloroplasts.

The light reactions are largely controlled by photosystems, sizable complexes of proteins and pigments (light-absorbing molecules) that are designed to capture light. Photosystem I (PSI) and Photosystem II are the two different types of photosystems (PSII).

Both photosystems have a variety of pigments that aid in the absorption of light energy as well as a unique pair of chlorophyll molecules at the reaction center. P700 denotes the special pair of photosystem I, while P600 denotes the unique pair of photosystem II.

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Answer:

[tex]\boxed {\boxed {\sf B. \ 1.5 *10^{23} \ formula \ units}}[/tex]

Explanation:

1 mole of any substance contains the same number of particles. The particles can vary (atoms, molecules, formula units), but there are always 6.022*10²³ particles. In this case, the particles are formula units of potassium nitrate or KNO₃.

Let's create a ratio.

[tex]\frac {6.022*10^{23} \ formula \ units \ KNO_3}{1 \ mol \ KNO_3}[/tex]

Since we are trying to find the formula units in 0.250 moles, we multiply by that number.

[tex]0.250 \ mol \ KNO_3 *\frac {6.022*10^{23} \ formula \ units \ KNO_3}{1 \ mol \ KNO_3}[/tex]

The units of moles of potassium nitrate cancel.

[tex]0.250 *\frac {6.022*10^{23} \ formula \ units \ KNO_3}{1 }[/tex]

The denominator of 1 can be ignored, so we can make a simple multiplication problem.

[tex]0.250 *{6.022*10^{23} \ formula \ units \ KNO_3}[/tex]

[tex]1.5055 * 10^{23} \ formula \ units \ KNO_3[/tex]

If we round to the nearest tenth, the 0 in the hundredth place tells us to leave the 5 in the tenth place.

[tex]1.5 *10^{23} \ formula \ units \ KNO_3[/tex]

0.250 moles of potassium nitrate is approximately equal to 1.5*10²³ formula units of potassium nitrate and choice B is correct.

x has the values (2.14 + √(23.288)) / 9.56 and  (2.14 - √(23.288)) / 9.56.

Quadratic equations are the degree two, one-variable polynomial equations of the form f(x) = ax^2 + bx + c = 0 with a, b, c, and R R and a 0 being the variables. In its most basic form, it is a quadratic equation where "a" denotes the leading coefficient and "c" is the absolute term of f(x). The values of x that satisfy the equation (, ) are the quadratic equation's roots.

Intricate relationships exist between square and quadrangle (another name for rectangle) difficulties and quadratic equations.

The Latin term quadratus, which means square, is where the word "quadratic" originates.

The quadratic formula or factoring can be used to get the solution to the problem 4.78x^2-2.14x-1.60=0.

x = (-b (b^2 - 4ac)) / (2a) where a = 4.78, b = -2.14, and c = -1.60 is the quadratic formula.

Plugging in the values we get:

x = (-(-2.14) ± √((-2.14)^2 - 4(4.78)(-1.60)) ) / (2(4.78))

x = (2.14 ± √(4.6016 + 18.688)) / 9.56

x = (2.14 ± √(23.288)) / 9.56

So the two values of x are:

x = (2.14 + √(23.288)) / 9.56 and x = (2.14 - √(23.288)) / 9.56

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Answer:

This is true. A seismograph measures the size of a volcano eruption by detecting the vibrations that are produced by the volcanic activity. The vibrations can then be converted into a numerical value that represents the magnitude of the eruption.

Explanation:

a) The balanced equation is :

C₂H₆   +  Cl₂ --->  C₂H₅Cl  + HCl

b) The percent yield is the 83.0 % %.

a) The balanced equation  is given below :

C₂H₆   +  Cl₂ --->  C₂H₅Cl  + HCl

b) mass of the ethane = 300 g

molar mass of the ethane = 30 g/mol

moles of the ethane = 300 / 30

                                  = 10 mol

mass of chlorine = 650 g

molar mass of the chlorine = 71 g /mol

moles = 650 / 71

          = 9.15 mol

it is clear the the chlorine is the limiting reactant.

1 mole of the chlorine produces the 1 mole of the C₂H₅Cl

moles of the C₂H₅Cl = 9.15 mol

mass of the C₂H₅Cl = 9.15 × 64.5

                                  = 590.175 g

The percent yield = (experimental yield / theoretical yield )  × 100 %

                              = ( 490 / 590 .175 ) × 100 %

                              = 83.0 %

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With 3.11 grams of sodium chloride we should start to make an aqueous solution of 50. 0 gm.

When water is used as a solvent then the solution is called the aqueous solution. Water is a good solvent which is naturally abundant and in chemistry, the word "solution" refers to the aqueous solution unless the solvent is specified. It is denoted by "aq".

Mass of aqueous solution = 50 gm

Mass percentage of sodium chloride = 6.213%

Let the mass of sodium chloride is N grams, then,

N = (50/100) × 6.213 gm

N = 0.5 × 6.213

N = 3.11 grams

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B) 2, 7, and 8 of the following molecules act as building blocks (monomers) of polypeptides.

You may think of it as several flavors that come together to form lengthy chains that we refer to as polypeptides, which are the fundamental components of proteins.

Peptide bonds bind the amino acids together in polypeptides. The interaction between the -carboxyl and -amino groups of two amino acids results in the formation of a dipeptide.

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We burn the things that have previously grown in the sunlight-carbohydrates. Hydrogen in the carbohydrates burns to form water which is very harmless. The carbon can be recycled into many different compounds.

The carbon in this material becomes carbon monoxide  carbon dioxide, (Poisonous to us mammals) and the carbon or char which can be a nutrient into the soil. Other things that can be burning in the waste will be toxic. Plants will absorb some  worst things that humans will spill out so carelessly like: lead, cadmium, and the other toxic metals—and these toxins are very dangerous in the atmosphere

So we can indeed to alter the composition of our atmosphere by burning things. Once our planet had a carbon dioxide in the atmosphere. It was a hell-hole here. It was very hot and the atmosphere was poisonous to higher life forms. Gradually life on the planet primarily plant life has been changed this atmosphere into something clean and wonderful. But we by our careless behaviour could return it into its original poisonous luckily the huge coniferous forests clean our air of carbon and the other pollution. We are eroding one factor of this margin after the another. Glaciation, wetlands, oceans, coral reefs, wild areas—these are our safeguards and one after another they are being lost.

--The given question is incomplete, the complete question is

"Explain how the following two processes alter the percentage of carbon dioxide in the atmosphere. I. Combustion (3) II. Respiration (3)".

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Physical properties  such as  mass, weights , density can be common for one or more substances hence cannot be used for identification while magnetism is unique for each substance ,hence used for identification.

Any property which describes the state of a physical system is called as a physical property.Changes in physical properties are used to describe changes between the states. They are often related to as observable properties.

Physical property which can be quantified is a physical quantity. These are also classified further with respect to their directionality. Physical properties are differentiated from chemical properties by the way they determine how a substance behaves in a chemical reaction.

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At an altitude of 18,000 feet, where the atmospheric pressure is 0.5 atm, the pressure is 7.5 pounds per square inch.

One square inch of any surface has 15 pounds of air sitting on top of it at sea level. That same square inch is only under 7.5 pounds per square inch of pressure at 18,000 feet.

The atmospheric pressure rises with increasing altitude. Contrary to popular belief, the graph shows that pressure decreases as altitude rises (moving to the right on the graph).

At sea level, the atmospheric pressure is 14 pounds per square inch. If we assume that the altitude is zero, we can see that the pressure is equal to 14 pounds per square inch. The atmospheric pressure rises as the altitude gets closer to sea level.

We observe that the pressure value rises as the altitude gets closer to sea level. As the altitude rises, the atmospheric pressure approaches 14 pounds per square foot. Only when the elevation is 0 miles above sea level does the pressure equal 14 pounds per square inch.

The pressure will therefore be 7.5 pounds per square inch if the air pressure in the atmosphere measures at 18,000 feet or 0.5 atm.

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Acceleration represented by the equation = Δv/Δt.

Answer:

The answer is A. a wave of vibrating electric and magnetic energy.

The specific heat capacity of the gaseous ethanol is less than the specific heat capacity liquid ethanol.

The specific heat capacity is given as :

Q = mc ΔT

where ,

Q = heat

m = mass

c = specific heat capacity

ΔT = temperature change

The heating curve represented the temperature , T in the y axis and the heat added at the x - axis. the slope is given as :

T / Q = 1 / C

T is the temperature and the c is the specific heat capacity.

Thus, the heat capacity of the gaseous ethanol is low as compared to the liquid ethanol.

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Answer:

See explanation

Explanation:

Barium sulphate is easily prepared by means of a double replacement reaction. A double replacement reaction is one in which the ions in each of the reactants exchange partners in the products.

For instance, we can decide to prepare barium sulphate by a double replacement reaction between sodium sulphate and barium chloride. The both starting materials are soluble compounds. However, the barium sulphate formed is an insoluble white precipitate. The precipitate is recovered by filtration, washed and dried.

The reaction equation is shown below;

Na2SO4(aq) + BaCl2(aq)  -------> BaSO4(s) + 2NaCl(aq)

Direct evidence for the interior of the Earth comes from measurements and samples that are taken directly from the Earth's interior. This can include things like rock samples from deep mines, or measurements of seismic waves that have traveled through the Earth.

One example of direct evidence is rock samples that have been brought to the surface by volcanic eruptions or other means. These samples can provide geologists with information about the composition and structure of the Earth's interior. For example, by studying the minerals in a rock sample, geologists can infer the temperatures and pressures that existed in the Earth's interior when the rock was formed.

Indirect evidence, on the other hand, is information that has been inferred from measurements or observations that are not taken directly from the Earth's interior. One example of indirect evidence is the study of seismic waves, which are waves of energy that travel through the Earth's interior in response to earthquakes or other disturbances. By measuring the speed at which these seismic waves travel through the Earth, geologists can infer the density and composition of the materials that make up the Earth's interior.