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2 years ago

how can there be so many different substances in the world if there are only a few elements that are common?

1 answer:

3 0

-- If there are only 10 elements in the universe that can make compound molecules, and a compound molecule can be formed by combining 1, 2, 3, or 4 different elements, then that's already the possibility of at least 400 different molecules.

-- There are many more than 10 elements that can combine to form compound molecules.

-- Every single "organic" molecule, of which there are thousands, is the combination of carbon with other elements.

-- Most all of the substances that can be distilled out of oil, including the paraffin waxes, the alcohols, gasoline, kerosene, butane, propane, octane, and natural gas, are made of just carbon, hydrogen, and oxygen, only with different numbers of each one.

-- Plastics, drugs, rubber, and DNA are examples of molecules that are made of hundreds of atoms.

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If you are driving 120 km/h along a straight road and you look to the side for 2.0 s , how far do you travel during this inatten

Delicious77 [7]

120 km / 60 min

2 km / 1 min

1 km / 30 sec

0.5 km / 15 sec

0.03333 km / sec

0.03333 km = 33.33 m

8 0

3 years ago

A heat engine cycle is executed with steam in the saturation dome. The pressure of steam is 1.1 MPa during heat addition and 0.3

klio [65]

Answer:The highest possible efficiency of this heat engine is 11%

Explanation:

Saturated water temperature at P1, Pressure in Heat addition,

1.1 MPa=185°C +273= 458K

Saturated water temperature at P2, Pressure in Heat rejection,

0.3MPa=133.5°C+ 273=406.5K

The highest possible efficiency of any heat engine is the Carnot efficiency given as

Carnot efficiency, ηmax = 1- (T2/ T1)

1- (406.5K/458K)

1-0.88755=0.112

=11%

8 0

2 years ago

How do you think scientists figure out what they think the population will be in 2050?

laila [671]

They would most likely use statistics on the increase/decrease in population from previous decades and centuries. In addition to these statistics, they could use the birth and death rate and ultimately predict the increase within these next 30 years. They must also take climate change and other environmental factors into consideration when formulating such a bold prediction.

4 0

3 years ago

Which experiment proved light was a wave?

pshichka [43]

Answer:

The answer is B) Double slit

8 0

2 years ago

A confined aquifer with a porosity of 0.15 is 30 m thick. The potentiometric surface elevation at two observation wells 1000 m a

AlekseyPX

Answer:

Part (a) The flow rate per unit width of the aquifer is 1.0875 m³/day

Part (b) The specific discharge of the flow is 0.0363 m/day

Part (c) The average linear velocity of the flow is 0.242 m/day

Part (d) The time taken for a tracer to travel the distance between the observation wells is 4132.23 days = 99173.52 hours

Explanation:

Part (a) the flow rate per unit width of the aquifer

From Darcy's law;

$q = -Kb\frac{dh}{dl}$

where;

q is the flow rate

K is the permeability or conductivity of the aquifer = 25 m/day

b is the aquifer thickness

dh is the change in th vertical hight = 50.9m - 52.35m = -1.45 m

dl is the change in the horizontal hight = 1000 m

q = -(25*30)*(-1.45/1000)

q = 1.0875 m³/day

Part (b) the specific discharge of the flow

$V = \frac{Q}{A} = \frac{q}{b} = -K\frac{dh}{dl}\\\\V = -(25 m/d).(\frac{-1.45 m}{1000 m}) = 0.0363 m/day$

V = 0.0363 m/day

Part (c) the average linear velocity of the flow assuming steady unidirectional flow

Va = V/Φ

Φ is the porosity = 0.15

Va = 0.0363 / 0.15

Va = 0.242 m/day

Part (d) the time taken for a tracer to travel the distance between the observation wells

The distance between the two wells = 1000 m

average linear velocity = 0.242 m/day

Time = distance / speed

Time = (1000 m) / (0.242 m/day)

Time = 4132.23 days

$= 4132.23 days *\frac{24 .hrs}{1.day} = 99173.52, hours$

4 0

2 years ago