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Crazy boy [7]
3 years ago
13

When you test starch with Barfoed’s reagent, what would be the answer, positive or negative?

Chemistry
1 answer:
rewona [7]3 years ago
7 0

Answer:

It would test positive.

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Of what four things are bones made
Elis [28]

Answer:

periosteum, compact bone, cancellous, bone marrow

5 0
2 years ago
Read 2 more answers
A 100-watt light bulb radiates energy at a rate of 100 J/s. (The watt, a unit of power or energy over time, is defined as 1 J/s.
Semmy [17]

Answer

2.7956 * 10^19 photons

Givens

  • Wavelength = λ = 525 * 10^-9 meters  [1 nmeter = 1*10^-9 meters]
  • c = 3 * 10^8 meters
  • E = ???
  • W = 100  watts
  • t = 1 second
  • h= plank's Constant = 6.26 * 10^-34 J*s

Formula

E = h * c / λ

W = E / t

Solution

E = 6.26 * 10^-34 j*s * 3 * 10^8 m/s /525 * 10^-9 (m)

The meters cancel out. So do the seconds. You are left with Joules as you should be.

E =  3.577 * 10^-18 Joules

What you have found is the energy of 1 photon.

Now you have to find the Joules from the watts.

W = E/t

100 * 1 second = 100 joules

1 photon contains 3.577 * 10 ^ - 18 Joules

x photon = 100 joules                        

1/x = 3.577 * 10^-18 / 100                          Cross multiply

100 = 3.577 * 10 ^ - 18 * x                         Divide both sides by 3.577 * 10 ^ - 18

100/3.577 * 10 ^ - 18 = 3.577 * 10 ^ - 18x / 3.577 * 10 ^ - 18

2.7956 * 10^19 photons = x


7 0
3 years ago
Which is the best explanation of why heat is released when
vazorg [7]
The answers is A. Reales energy stored in chemical bonds
6 0
3 years ago
Explain the part that the subduction zones play in the cycling of matter between Earth’s crust and mantle.
WARRIOR [948]

Explanation:

The earth’s crust is broken into separate pieces called tectonic plates (Fig. 7.14). Recall that the crust is the solid, rocky, outer shell of the planet. It is composed of two distinctly different types of material: the less-dense continental crust and the more-dense oceanic crust. Both types of crust rest atop solid, upper mantle material. The upper mantle, in turn, floats on a denser layer of lower mantle that is much like thick molten tar.

Each tectonic plate is free-floating and can move independently. Earthquakes and volcanoes are the direct result of the movement of tectonic plates at fault lines. The term fault is used to describe the boundary between tectonic plates. Most of the earthquakes and volcanoes around the Pacific ocean basin—a pattern known as the “ring of fire”—are due to the movement of tectonic plates in this region. Other observable results of short-term plate movement include the gradual widening of the Great Rift lakes in eastern Africa and the rising of the Himalayan Mountain range. The motion of plates can be described in four general patterns:

<p><strong>Fig 7.15.</strong> Diagram of the motion of plates</p>

Collision: when two continental plates are shoved together

Subduction: when one plate plunges beneath another (Fig. 7.15)

Spreading: when two plates are pushed apart (Fig. 7.15)

Transform faulting: when two plates slide past each other (Fig. 7.15)

The rise of the Himalayan Mountain range is due to an ongoing collision of the Indian plate with the Eurasian plate. Earthquakes in California are due to transform fault motion.

Geologists have hypothesized that the movement of tectonic plates is related to convection currents in the earth’s mantle. Convection currents describe the rising, spread, and sinking of gas, liquid, or molten material caused by the application of heat. An example of convection current is shown in Fig. 7.16. Inside a beaker, hot water rises at the point where heat is applied. The hot water moves to the surface, then spreads out and cools. Cooler water sinks to the bottom.

<p><strong>Fig. 7.16.</strong> In this diagram of convection currents in a beaker of liquid, the red arrows represent liquid that is heated by the flame and rises to the surface. At the surface, the liquid cools, and sinks back down (blue arrows).</p><br />

Earth’s solid crust acts as a heat insulator for the hot interior of the planet. Magma is the molten rock below the crust, in the mantle. Tremendous heat and pressure within the earth cause the hot magma to flow in convection currents. These currents cause the movement of the tectonic plates that make up the earth’s crust.

8 0
3 years ago
Given the following equation: Cu + 2 AgNO3 ---&gt; Cu(NO3)2 + 2
Temka [501]

Given the following equation; Cu + 2AgNO3 = Cu(NO3)2 + 2Ag, 48.97 grams of Cu are needed to react with 262g of AgNO3.

<h3>How to calculate mass of substances?</h3>

The mass of a substance can be calculated using the following steps:

Cu + 2AgNO3 = Cu(NO3)2 + 2Ag

1 mole of Cu react with 2 moles of AgNO3

  • Molar mass of AgNO3 = 169.87 g/mol
  • Molar mass of Cu = 63.5g/mol

moles of AgNO3 = 262g/169.87g/mol = 1.54mol

1.54 moles of AgNO3 will react with 0.77 moles of Cu.

mass of Cu = 0.77 × 63.5 = 48.97g

Therefore, given the following equation; Cu + 2AgNO3 = Cu(NO3)2 + 2Ag, 48.97 grams of Cu are needed to react with 262g of AgNO3.

Learn more about mass at: brainly.com/question/6876669

8 0
2 years ago
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