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Elza [17]
3 years ago
5

6. The variable that a scientist changes on purpose to test a hypothesis is the

Chemistry
1 answer:
nirvana33 [79]3 years ago
8 0

Answer:

the amount of water and the growth

Explanation:

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A horizontal pipe 15 cm in diameter and 4 m long is buried in the earth at a depth of 20 cm. The pipe-wall temperature is 75 deg
Basile [38]

Explanation:

The given data for case (1) is as follows.

  h = 20 cm = 0.2 m

Assuming that a rectangular slab is placed above the pipe and we will calculate the heat transfer as follows.

              Q = kA \frac{\Delta T}{L}

  where,    A = area

                  L = length

                  k = thermal conductivity = 0.8 W/m

             \Delta T = change in temperature.

Therefore, putting the given values into the above formula as follows.

            Q = kA \frac{\Delta T}{L}

                = 0.8 W/m \times (4 m \times 0.15 m) \frac{75 - 5}{0.2}

                = 168 W

For case (2), h = 180 cm = 1.8 m

Therefore, heat lost will be calculated as follows.

                       Q = kA \frac{\Delta T}{L}

                           = 0.8 W/m \times (4 m \times 0.15 m) \frac{75 - 5}{1.8}

                           = 18.67 W

Thus, we can conclude that 18.67 W heat lost if the pipe was buried at a depth of 180 cm.

8 0
3 years ago
What role does the wire play in voltaic cell
VashaNatasha [74]
It allows electrons to flow from the anode to the cathode.
8 0
2 years ago
A very old tree limb contains an amount of carbon-14 that is approximately 1/8 of the current atmospheric 14C levels.. Calculate
Tomtit [17]

A.       The radioactive decay equation is N = N0e^{-ln(2)*t/T }

where T is the half-life (5730 years), N0 is the number of atoms at time t = 0 and N is the number at time t.

Rewriting this as:

(N/N0) = e^{-ln(2)*t/T }

Since N = (1/8) N0 and substituting known values:

1/8 = e^{-ln(2)*t/5730}

Taking ln of both sides:

ln(1/8)= -ln(2)*t/5730

t = - 5730 * ln(1/8) / ln (2)

t = 17,190 years

The tree was cut down 17,190 years ago.

B.   N0 = 1,500,000 carbon-14 atoms

Since N = (1/8) N0

N = 187,500 carbon atoms left

3 0
3 years ago
The pressure of a sample of argon gas was increased from 3.14 atm to 7.98 at a constant temperature. If the final volume of argo
noname [10]

Answer:

<h2>36.09 L</h2>

Explanation:

The initial volume can be found by using the formula for Boyle's law which is

P_1V_1 = P_2V_2

where

P1 is the initial pressure

P2 is the final pressure

V1 is the initial volume

V2 is the final volume.

Since we're finding the initial volume

V_1 =  \frac{P_2V_2}{P_1}  \\

We have

V_1 =  \frac{7.98 \times 14.2}{3.14} =   \frac{113.316}{3.14}  \\  = 36.0878...

We have the final answer as

<h3>36.09 L</h3>

Hope this helps you

8 0
2 years ago
1. How many moles of oxygen gas are needed to form 21.8 liters of water vapor?
BaLLatris [955]

0.781 moles

Explanation:

We begin by balancing the chemical equation;

O₂ (g) + 2H₂ (g) → 2H₂O (g)

21.8 Liters = 21.8 Kgs

To find how many moles are in 28.1 Kg H₂O;

Molar mass of H₂O = 18 g/mol

28.1/18

= 1.56 moles

The mole ratio between water vapor and oxygen is;

1 : 2

x : 1.56

2x = 1.56

x = 1.56 / 2

x =  0.781

0.781 moles

7 0
2 years ago
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