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Fofino [41]
3 years ago
8

Which statements are true about the periodic table? Check all that apply. A. The periodic table is organized by atomic number. B

. There are two different ways to number the groups of the periodic table. C. Each box on the table represents one element. D. Elements in the same row of the periodic table have the same number of electron shells.
Physics
1 answer:
natulia [17]3 years ago
5 0
Let's evaluate each answer closely:
<span>A. The periodic table is organized by atomic number.
This statement is true the atomic number is what defines each element and is the number of protons and electrons in a neutral atom

B. There are two different ways to number the groups of the periodic table.
This is true.  The more modern method is to number the groups 1 - 18.  Earlier models used a Roman numeral and either an A or B to denote groups.
 
C. Each box on the table represents one element.
THis is also true.  Each box contains a unique element.

D. Elements in the same row of the periodic table have the same number of electron shells.
This is true.  The row that the element is on is also the number of electron shells that are in the element.
</span>
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A young man exerted a force of 9,000 N on a stalled car but was unable to move it. How much work was done?
olasank [31]
W=F*s
W=9000*0
W=0
W:Work
F:Force
s:Distance
5 0
3 years ago
Violet light of wavelength 405 nm ejects electrons with a maximum kinetic energy of 0.890 eV from a certain metal. What is the b
AleksandrR [38]

Answer:

  Ф = 2.179 eV

Explanation:

This exercise has electrons ejected from a metal, which is why it is an exercise on the photoelectric effect, which is explained assuming the existence of energy quanta called photons that behave like particles.

            E = K + Ф

the energy of the photons is given by the Planck relation

            E = h f

we substitute

           h f = K + Ф

           Ф= hf - K

the speed of light is related to wavelength and frequency

            c = λ f

            f = c /λ

            Φ = \frac{hc}{\lambda } - K

let's reduce the energy to the SI system

            K = 0.890 eV (1.6 10⁻¹⁹ J / 1eV) = 1.424 10⁻¹⁹ J

calculate

           Ф = 6.63 10⁻³⁴ 3 10⁸/405 10⁻⁹  -1.424 10⁻¹⁹

           Ф = 4.911 10⁻¹⁹ - 1.424 10⁻¹⁹

           Ф = 3.4571 10⁻¹⁹ J

         

we reduce to eV

           Ф = 3.4871 10⁻¹⁹ J (1 eV / 1.6 10⁻¹⁹ J)

           Ф = 2.179 eV

4 0
2 years ago
Can someone help me wit hthis science question?
klemol [59]

Answer:

see explanation  

Explanation:

There is an increasing demand for materials and natural resources from a growing global population, especially those in more economically developed countries. The world's resources are being used up more quickly. The consumption of resources is spread unequally between MEDCs (more economically developed countries), who use more resources, and LEDCs (less economically developed countries), who use less.

The gap between the rich and poor is more evident when the resources are shared so unevenly and unfairly and natural resources like materials and natural energy cannot reach the demand of the people which can have consequences and be very difficult to manage. Having a lack of these materials in a country can result in prices going up for them, and the industry could be harder to work in because of a lack of materials.

6 0
3 years ago
Who invented the wedge simple machine and why?
Lelu [443]

Answer:

Gene Sarazen began to win tournaments in 1935 with a new club he had invented that was specialized for sand play. He is hailed as the inventor of the sand wedge.

Explanation:

A wedge is a triangular shaped tool, and is a portable inclined plane, and one of the six classical simple machines. It can be used to separate two objects or portions of an object, lift up an object, or hold an object in place. It functions by converting a force applied to its blunt end into forces perpendicular (normal) to its inclined surfaces. The mechanical advantage of a wedge is given by the ratio of the length of its slope to its width.[1][2] Although a short wedge with a wide angle may do a job faster, it requires more force than a long wedge with a narrow angle.

The force is applied on a flat, broad surface. This energy is transported to the pointy, sharp end of the wedge, hence the force is transported.

The wedge simply transports energy and collects it to the pointy end, consequently breaking the item. In this way, much pressure is put on a thin area.

3 0
3 years ago
Dr. Aloysius found four homogeneous mixtures, but he thinks that only three are alloys. He tests each one and determines their e
Lina20 [59]

Answer:

A. carbon and boron

Explanation:

Carbon and boron is not an alloy.

An allow forms between metals and metals using their huge electron could.

Carbon is a non-metal, boron is a also a non-metal

Two non-metals combining together does not make an alloy.

Iron, nickel, aluminum  are all metals.

6 0
3 years ago
Read 2 more answers
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