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4 years ago

22. When looking at the halogens on the periodic table, how does the number of valence electrons change as the

Physics

1 answer:

Gennadij [26K]4 years ago

7 0

Answer:

The total number of valence electrons per atom does not change. It remains at 7 (as opposed to 1 in the options.)

Explanation:

The periodic table organizes elements with the same number of valence electrons in the same column.

All the halogens (F, Cl, Br, etc.) are found in the same column (the second column from the right) on the periodic table. The all have the same number of valence electrons per atom.

All elements in the right-most column (the one with all the noble gas elements) contain 8 valence electrons per atom (a full valence shell.) Since the halogens are to the left of the noble gas elements by only one place, each would contain $(8 - 1) = 7$ valence electrons.

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We are given
the maximum allowed leakage of radiation from a microwave = 5.0mW/cm²
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3 years ago

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4 years ago

Read 2 more answers

Here are three pairs of initial and final positions, respectively, along an x-axis. Which pair gives a

Sladkaya [172]

Answer:

(b)-3 m,-7 m

Explanation:

Displacement is a vector quantity that connects the initial position of an object to its final position after a certain motion.

Mathematically, displacement can be written as:

$d=x_f - x_i$

where

$x_f$ is the final position

$x_i$ is the initial position

The direction of this vector is from the initial position to the final position.

In order to calculate the displacement of an object, therefore, it is necessary to correctly take into account the sign of each motion, which gives the direction of each motion.

Let's analyze the three cases:

(a) -3 m, +5 m;

In this case, the object moves 3 m in the negative direction first, and then 5 meters in the positive direction; so the net displacement is

d = -3 + 5 = +2 m

(b)-3 m,-7 m;

In this case, the object moves 3 m in the negative direction first, and then 3 meters in the negative direction; so the net displacement is

d = -3 - 7 = -10 m

In this case, the object moves 7 m in the positive direction first, and then 3 meters in the negative direction; so the net displacement is

d = +7 + (-3) = +4 m

So, the only situation in which we have a net negative displacement is situation b).

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3 years ago

A movie stunt performer is filming a scene where he swings across a river on a vine. The safety crew must use a vine with enough

Anuta_ua [19.1K]

Answer:

$T = 250.674\,N$

Explanation:

The vine experiments a centripetal acceleration while swinging (the stuntsman experiments a centrifugal acceleration), whose most critical point occurs at the bottom and can be described by the Newton's Laws:

$\Sigma F = T - m\cdot g = -m\cdot \frac{v^{2}}{R}$

The minimum tension force that the vine must be able to support without breaking is:

$T = m\cdot g - m\cdot \frac{v^{2}}{R}$

$T = m\cdot \left(g-\frac{v^{2}}{R} \right)$

$T = (82\,kg)\cdot \left[9.807\,\frac{m}{s^{2}}-\frac{\left(9\,\frac{m}{s} \right)^{2}}{12\,m} \right]$

$T = 250.674\,N$

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4 years ago

Sometimes students are taught that "air expands as it is heated". And sometimes they are taught that "as air expands it cools".

hram777 [196]

Answer:

Both are true under specific circumstances. And are related to Boyle's law. volume and pressure in a gas are inversely proportional.

Explanation:

There is a tendency to entropy in our reality, that is, in particular true and visible with gases, they tend to occupy the whole space where they are confined, when we heat a volume of gas, then the movement of the particles and in consequence the pressure of the gas increases and to compensate this the volume tends to be increased too, according to Boyle's law. And the opposite happens when the volume is increased, then the pressure is relieved and since the particles are further one from each other, then the temperature is lower, and therefore it cools down.

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4 years ago