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Aliun [14]
3 years ago
9

A graph of coal reserves in the United States versus time slopes downward.

Chemistry
2 answers:
Dafna1 [17]3 years ago
4 0

Answer:

increased

Explanation:

I believe to be increased ,because the coal is a natural resource to be used.

i really hope it helps

tatyana61 [14]3 years ago
3 0
I remember I had this question before on USA test prep and it’s increased
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The antibiotic doxycycline is used to treat Lyme disease. A 100 mg dose of the antibiotic consists of 59.5 mg of C, 5.40 mg of H
never [62]

Answer:

C₁₁H₁₂NO₄

Explanation:

In order to determine the empirical formula of doxycycline, we need to follow a series of steps.

Step 1: Determine the centesimal composition

C: 59.5 mg/100 mg × 100% = 59.5%

H: 5.40 mg/100 mg × 100% = 5.40%

N: 6.30 mg/100 mg × 100% = 6.30%

O: 28.8 mg/100 mg × 100% = 28.8%

Step 2: Divide each percentage by the atomic mass of the element

C: 59.5 /12.0 = 4.96

H: 5.40/1.00 = 5.40

N: 6.30/14.0 = 0.450

O: 28.8/16.0 = 1.80

Step 3: Divide all the numbers by the smallest one

C: 4.96/0.450 = 11

H: 5.40/0.450 = 12

N: 0.450/0.450 = 1

O: 1.80/0.450 = 4

The empirical formula of doxycycline is C₁₁H₁₂NO₄

5 0
3 years ago
Which statements are true about light waves? (Select all that apply.)
Diano4ka-milaya [45]

Answer:

A C D I believe

Explanation:

4 0
2 years ago
A 240.0 gram piece of copper is dropped into 400.0 grams of water at 24.0 °C. If the final temperature of water is 42.0 °C, what
ludmilkaskok [199]

The initial temperature of the copper piece if a 240.0 gram piece of copper is dropped into 400.0 grams of water at 24.0 °C is 345.5°C

<h3>How to calculate temperature?</h3>

The initial temperature of the copper metal can be calculated using the following formula on calorimetry:

Q = mc∆T

mc∆T (water) = - mc∆T (metal)

Where;

  • m = mass
  • c = specific heat capacity
  • ∆T = change in temperature

According to this question, a 240.0 gram piece of copper is dropped into 400.0 grams of water at 24.0 °C. If the final temperature of water is 42.0 °C, the initial temperature of the copper is as follows:

400 × 4.18 × (42°C - 24°C) = 240 × 0.39 × (T - 24°C)

30,096 = 93.6T - 2246.4

93.6T = 32342.4

T = 345.5°C

Therefore, the initial temperature of the copper piece if a 240.0 gram piece of copper is dropped into 400.0 grams of water at 24.0 °C is 345.5°C.

Learn more about temperature at: brainly.com/question/15267055

8 0
2 years ago
Which substance is not a structural isomer of hexyne?
stich3 [128]

Answer:

c) 3,3-dimethylpent-1-yne

5 0
3 years ago
8. The time period of artificial satellite in a circular orbit of radius R is T. The radius of the orbit in which time period is
Elena-2011 [213]

Explanation:

It is given that,

The time period of artificial satellite in a circular orbit of radius R is T. The relation between the time period and the radius is given by :

T^2\propto R^3

The radius of the orbit in which time period is 8T is R'. So, the relation is given by :

(\dfrac{T}{T'})^2=(\dfrac{R}{R'})^3

(\dfrac{T}{8T})^2=(\dfrac{R}{R'})^3  

\dfrac{1}{64}=(\dfrac{R}{R'})^3

R'=4\times R

So, the radius of the orbit in which time period is 8T is 4R. Hence, this is the required solution.  

4 0
3 years ago
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