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3 years ago

12

Scientific knowledge is open to change as new information is discovered. Which of the following would NOT be a result of new sci

entific knowledge?
A
Scientists discover that a type of fungus on this log does not require oxygen for absorption and change the classification system.

B
Scientists publish an article that mentions the historic decline in the population of blue stain fungi.

C
Scientists classify a recently discovered bacterium living on this log using generally accepted naming procedures.

D
Scientists discover a bacterium living on this log that is multicellular and revise their classification

1 answer:

amid [387]3 years ago

4 0

B would be the answer

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If the same amount of heat is added to 25.0 g of each of the metals, which are all at the same initial temperature, which metal

AVprozaik [17]

Answer:

The bismuth sample.

Explanation:

The specific heat $c$ of a substance (might not be a metal) is the amount of heat required for heating a unit mass of this substance by unit temperature (e.g., $\rm 1\; ^{\circ}C$ .) The formula for specific heat is:

$\displaystyle c = \frac{Q}{m \cdot \Delta T}$ ,

where

$Q$ is the amount of heat supplied.
$m$ is the mass of the sample.
$\Delta T$ is the increase in temperature.

In this question, the value of $Q$ (amount of heat supplied to the metal) and $m$ (mass of the metal sample) are the same for all four metals. To find $\Delta T$ (change in temperature,) rearrange the equation:

$\displaystyle c \cdot \Delta T = \frac{Q}{m}$ ,

$\displaystyle \Delta T = \frac{Q}{c \cdot m}$ .

In other words, the change in temperature of the sample, $\Delta T$ can be expressed as a fraction. Additionally, the specific heat of sample, $c$ , is in the denominator of that fraction. Hence, the value of the fraction would be the largest for sample with the smallest specific heat.

Make sure that all the specific heat values are in the same unit. Find the one with the smallest specific heat: bismuth ( $\rm 0.123 \; J \cdot g\cdot \,^{\circ}C^{-1}$ .) That sample would have the greatest increase in temperature. Since all six samples started at the same temperature, the bismuth sample would also have the highest final temperature.

3 0

3 years ago

How many liters of 3.5 M solution can be made using 23 moles of LiBr *must show work to get credit*

MrMuchimi

<u>Answer:</u> 6.57 L of solution can be made.

<u>Explanation:</u>

Molarity is defined as the amount of solute expressed in the number of moles present per liter of solution. The units of molarity are mol/L. The formula used to calculate molarity:

$\text{Molarity of solution}=\frac{\text{Moles of solute}}{\text{Volume of solution (L)}}$ .....(1)

Given values:

Molarity of LiBr = 3.5 M

Moles of LiBr = 23 moles

Putting values in equation 1, we get:

$3.5mol/L=\frac{23mol}{\text{Volume of solution}}\\\\\text{Volume of solution}=\frac{23mol}{3.5mol/L}=6.57L$

Hence, 6.57 L of solution can be made.

5 0

3 years ago

rate of a certain reaction is given by the following rate law: rate Use this information to answer the questions below. What is

Sunny_sXe [5.5K]

Complete Question

The rate of a certain reaction is given by the following rate law:

$rate = k [H_2][I_2]$

rate Use this information to answer the questions below.

What is the reaction order in $H_2$ ?

What is the reaction order in $I_2$ ?

What is overall reaction order?

At a certain concentration of H2 and I2, the initial rate of reaction is 2.0 x 104 M / s. What would the initial rate of the reaction be if the concentration of H2 were doubled? Round your answer to significant digits. The rate of the reaction is measured to be 52.0 M / s when [H2] = 1.8 M and [I2] = 0.82 M. Calculate the value of the rate constant. Round your answer to significant digits.

Answer:

The reaction order in $H_2$ is n = 1

The reaction order in $I_2$ is m = 1

The overall reaction order z = 2

When the hydrogen is double the the initial rate is $rate_n = 4.0*10^{-4} M/s$

The rate constant is $k = 35.23 \ M^{-1} s^{-1}$

Explanation:

From the question we are told that

The rate law is $rate = k [H_2][I_2]$

The rate of reaction is $rate = 2.0 *10^{4} M /s$

Let the reaction order for $H_2$ be n and for $I_2$ be m

From the given rate law the concentration of $H_2$ is raised to the power of 1 and this is same with $I_2$ so their reaction order is n=m=1

The overall reaction order is

$z = n +m$

$z =1 +1$

$z =2$

At $rate = 2.0 *10^{4} M /s$

$2.0*10^{4} = k [H_2] [I_2] ---(1)$

= > $k = \frac{2.0*10^{4}}{[H_2] [I_2] }$

given that the concentration of hydrogen is doubled we have that

$rate = k [2H_2] [I_2] ----(2)$

=> $k = \frac{rate_n }{ [2H_2] [I_2]}$

So equating the two k

$\frac{2.0*10^{4}}{[H_2] [I_2] } = \frac{rate_n }{ [2H_2] [I_2]}$

=> $rate_n = 4.0*10^{-4} M/s$

So when

$rate_x = 52.0 M/s$

$[H_2] = 1.8 M$

$[I_2] = 0.82 \ M$

We have

$52 .0 = k(1.8)* (0.82)$

$k = \frac{52 .0}{(1.8)* (0.82)}$

$k = 35.23 M^{-2} s^{-1}$

3 0

2 years ago

The half life of potassium 40 is approximately 1.25 billion years. An igneous rock is found to contain about 1/4 of its original

vodomira [7]

Answer:

2.5 billion years

Explanation:

4 0

3 years ago

Describe at least two methods to separate a mixture of small copper and iron beads

bekas [8.4K]

<span>A fast way to separate the mixture would be to use a magnet. Iron is magnetic while copper is not. The second method would be to visually separate them since iron and copper distinctly different colors.</span>

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3 years ago

Read 2 more answers