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3 years ago

What color do we see when all light is reflected?

Chemistry

1 answer:

luda_lava [24]3 years ago

8 0

Answer:

white

Explanation:

If only blue light is shone onto a red shirt, the shirt would appear black, because the blue would be absorbed and there would be no red light to be reflected. White objects appear white because they reflect all colors. Black objects absorb all colors so no light is reflected.

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In the figure below, two nonpolar molecules are interacting.Which interaction would most likely cause these molecules to repel e

Fed [463]

Two non-polar molecules are most likely to interact by
induced dipole-induced dipole interaction.

Non-polar substances do not have a permanently established charge distribution due to similar electron affinities of the atoms that are present. Moreover, due to the absence of a polar hydrogen, they cannot exhibit hydrogen bonding. They interact with one another by induced dipole-induced dipole interactions which arise from the molecules of the substances coming into close vicinity of one another.

6 0

3 years ago

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The unit cell for cr2o3 has hexagonal symmetry with lattice parameters a = 0.4961 nm and c = 1.360 nm. If the density of this ma

IRINA_888 [86]

To calculate the packing factor, first calculate the area and volume of unit cell.

Area is calculated as:

$A=6R^{2}\sqrt{3}$

Here, R is radius and is related to a as follows:

$R=\frac{a}{2}$

Putting the value in expression for area,

$A=6(\frac{a}{2})^{2}\sqrt{3}=1.5a^{2}\sqrt{3}$

The value of a is 0.4961 nm

Since, $1 nm=10^{-7}cm$

Thus, $0.4961 nm=4.961\times 10^{-8} cm$

Putting the value,

$Area=1.5(4.961\times 10^{-8}cm)^{2}\sqrt{3}=6.39\times 10^{-15}cm^{2}$

Now, volume can be calculated as follows:

$V=Area\times c$

The value of c is 1.360 nm or $1.360\times 10^{-7} cm$

Putting the value,

$V=(6.39\times 10^{-15}cm^{2})\times (1.360\times 10^{-7} cm)=8.7\times 10^{-22}cm^{3}$

now, number of atom in unit cell can be calculated by using the following formula:

$n=\frac{\rho N_{A}V_{c}}{A}$

Here, A is atomic mass of $Cr_{2}O_{3}$ is 151.99 g/mol.

Putting all the values,

$n=\frac{(5.22 g/cm^{3})(6.023\times 10^{23} mol^{-1})(8.7\times 10^{-22}cm^{3})}{(151.99 g/mol)}\approx 18$

Thus, there will be 18 $Cr_{2}O_{3}$ units in 1 unit cell.

Since, there are 2 Cr atoms and 3 oxygen atoms thus, units of chromium and oxygen will be 2×18=36 and 3×18=54 respectively.

The atomic radii of $Cr^{3+}$ and $O^{2-}$ is 62 pm and 140 pm respectively.

Converting them into cm:

$1 pm=10^{-10}cm$

Thus,

$r_{Cr^{3+}}=6.2\times 10^{-9}cm$

and,

$r_{O^{2-}}=1.4\times 10^{-8}cm$

Volume of sphere will be sum of volume of total number of cations and anions thus,

$V_{S}=V_{Cr^{3+}}+V_{O^{2-}}$

Since, volume of sphere is $V=\frac{4}{3}\pi r^{3}$ ,

$V_{S}=36\left ( \frac{4}{3}\pi (r_{Cr^{3+})^{3}} \right )+54\left ( \frac{4}{3}\pi (r_{O^{2-})^{3}} \right )$

Putting the values,

$V_{S}=36\left ( \frac{4}{3}(3.14) (6.2\times 10^{-9} cm)^{3}} \right )+54\left ( \frac{4}{3}(3.14) (1.4\times 10^{-8} cm)^{3}} \right )=6.6\times 10^{-22}\times 10^{-8}cm^{3}$

The atomic packing factor is ratio of volume of sphere and volume of crystal, thus,

$packing factor=\frac{V_{S}}{V_{C}}=\frac{6.6\times 10^{-22}cm^{3}}{8.7\times 10^{-22}cm^{3}}=0.758$

Thus, atomic packing factor is 0.758.

6 0

3 years ago

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How many neutrons does element X have if its atomic number is 30 and its mass number is 70?

Yanka [14]

The answer is 40.

We can solve this by finding out the number of protons, and neutrons. Atomic number of an element means the number of protons in that element. So, the atom has 30 protons if the atomic number is 30.

On the other hand, mass number is the total number of protons and neutrons, but not electrons, because they're too light comparing to the other 2. Therefore, we can simply solve the number of neutrons in the atom by subtracting the number of protons from the mass number. 70 - 30 = 40.

Therfore, the number of neutrons is 40.

3 0

3 years ago

The physical world around us behaves as it does partly because it’s made of a huge number of tiny molecules, each behaving rando

eduard

1. Weird things like the one described above do not happen on a ramdom basis becuause molecules usually move within any enclosure in a ramdom manner. Thus, it is not possible for some types of particles to aggregate in one point while other types of molecule aggreagate in another point. Based on the kinetic energy that is available for each particle, each particle will move random
through the available space, colliding with one another and with the wall of container.

2. It will be a difficult thing to live in a Maxwell' demon world because, things will happen unpredictably and one will never know what to expect next because anything can happen at anytime. For instance, if one is drinking a glass of water, some of the particles of the water may just decide to aggregate to one part of the cup and start boiling. So, for someone who is taking a glass of water, the water may start boiling right inside his mouth when he is drinking, that will be a bad experience. When one is driving a car, the petrol particles may just decide to freeze up when one is busy speeding on the highway; that can cause a very serious accident. Thus, a world where the Maxwell law operates will be a chaotic world.

3 0

3 years ago

Calculate the change in temperature (ΔT) that occurs when 8000 J of energy (q) is used to heat up a mass (m) of 75 g of water. (

pickupchik [31]

Answer:

The change in temperature that occurs when 8000 J of heat is used by a mass 75 g of water is 25.4 °C

Explanation:

H = mc ΔT

m = 75 g

c = 4. 200 J/ g °C

H = 8000 J

ΔT =?

Rearranging the formula, making ΔT the subject of formula;

ΔT = H / m c

ΔT = 8000 / 75 * 4.200

ΔT = 8000 / 315

ΔT = 25.4 °C

8 0

3 years ago

Read 2 more answers