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4 years ago

Pleaseeee helppp

Chemistry

1 answer:

Dmitry [639]4 years ago

4 0

A chemical change

Explanation:

In this reaction, a chemical change has occurred, here are some indicators of chemical changes from the reaction;

Chemical changes are changes in which new products are formed.

Formation of bubbles and precipitates: these are new substances that indicates a chemical change. The bubbles and insoluble precipitate are good indicators of chemical change.
A temperature change that is large; This is also typifies chemical changes. When temperature rises in reaction, a chemical change has occurred.
The bubbles and precipitates cannot be combined to give the reactants. The reaction is irreversible.

learn more:

Chemical change brainly.com/question/9388643

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I think C (Might not be true)

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3 years ago

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while ionic compounds in the solid state do not conduct electricity, when they are melted, electric current

evablogger [386]

Answer:

Explanation:

Ionic (or electrovalent) compounds conduct electricity when there they are in the aqueous state/solution because the charges of ions of these compounds are what carry the electric charges in the aqueous solution as a result of free movement within the aqueous solution which they do not "have" when in there solid state (where they have a highly restricted movement/compacted structure).

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3 years ago

Write the condensed ground-state electron configurations of these transition metal ions, and state which are paramagnetic:

jok3333 [9.3K]

Answer:

a) Mo the electron configuration: 42Mo: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d4

Mo3+ - is Paramagnetic

b) Au - [Xe] 4f14 5d10 6s1

For Au+ is not paramagnetic

c) Mn - [Ar] 3d5 4s2

Mn2+ is paramagnetic

d)Hf -[Xe] 4f¹⁴ 5d² 6s²

Hf2+ is not paramagnetic

Explanation:

An atom becomes positively charged when it looses an electron.

Diamagnetism in atom occurs whenever two electrons in an orbital paired equalises with a total spin of 0.

Paramagnetism in atom occurs whenever at least one orbital of an atom has a net spin of electron. That is a paramagnetic electron is just an unpaired electron in the atom.

Here is a twist even if an atom have ten diamagnetic electrons, the presence of at least one paramagnetic electron, makes it to be considered as a paramagnetic atom.

Simply put paramagnetic elements are one that have unpaired electrons, whereas diamagnetic elements do have paired electron.

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3 years ago

What is the kinetic energy of the emitted electrons when cesium is exposed to UV rays of frequency 1.0×1015Hz?

RideAnS [48]

The kinetic energy of the emitted electrons of cesium when it is exposed to UV rays of frequency $1.0 \times {10^{15}}\;{\text{Hz}}$ is $\boxed{6.63 \times {{10}^{ - 19}}\;{\text{J}}}$

Further Explanation:

Photoelectric effect:

When light is made to fall on any substance, electrons are emitted from it. This is known as the photoelectric effect and the emitted electrons are called photoelectrons. The electrons are emitted because of the transference of energy from light to the electrons.

Cesium is a member of the alkali metal group so it is highly reactive and shows photoelectric effect to the maximum extent. It can remove its electron so easily because of its atomic size. Due to large atomic size of cesium, its outermost electrons are held very less tightly to the nucleus and therefore removed easily.

According to the Planck-Einstein equation, the energy is proportional to the frequency and is expressed as follows:

${\mathbf{E=h\nu }}$ ......(1)

Here,

${\text{E}}$ is the energy.

$h$ is the Plank’s constant.

$\nu$ is the frequency.

The frequency of UV rays is $1.0 \times {10^{15}}\;{\text{Hz}}$ or $1.0 \times {10^{15}}\;{{\text{s}}^{ - 1}}$

The value of Planck’s constant is $6.626 \times {10^{ - 34}}\;{\text{J}}\cdot{\text{s}}$ .

Substitute these values in equation (1)

$\begin{aligned}{\text{E}}&=\left( {6.626 \times {{10}^{ - 34}}\;{\text{J}}\cdot{\text{s}}}\right)\left( {1.0 \times {{10}^{15}}\;{{\text{s}}^{ - 1}}}\right)\\&=6.63\times {10^{ - 19}}\;{\text{J}}\\\end{aligned}$

But when electrons are ejected out from the surface of the substance, all of its energy is considered as kinetic energy.

So the kinetic energy of the electrons is ${\mathbf{6}}{\mathbf{.63 \times 1}}{{\mathbf{0}}^{{\mathbf{ - 19}}}}\;{\mathbf{J}}$ .

Learn more:

1. Statement about subatomic particle: brainly.com/question/3176193

2. The energy of a photon in light: brainly.com/question/7590814

Answer details:

Grade: Senior School

Subject: Chemistry

Chapter: Structure of the atom

Keywords: kinetic energy, frequency, energy, photoelectric effect, Planck's constant, light, electrons, photoelectrons, proportional, transference, reactive, cesium.

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Answer:

Lithium does form a peroxide as well as an oxide on burning in air and I suspect the low temperature reaction with air forms a significant amount of peroxide.

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