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3 years ago

Which mineral has the same hardness as a fingernail?

Chemistry

2 answers:

Marina86 [1]3 years ago

4 0

Gypsum has the same hardness as a fingernail

ipn [44]3 years ago

4 0

<h3>Answer:</h3>

Gypsum

<h3>Explanation:</h3>

The hardness of minerals or substances is measured qualitatively using Mohs Scale. In this scale the hardness is measured qualitatively by characterizing the resistance shown by one substance when rubbed against second substance. Therefore, greater points are given to those substances which are capable of making scratches on other substances. The Mohs Scale of given compounds is as follow,

Diamond 10

Fluorite 4

Topaz 8

Gypsum 1.5 to 2

While the hardness value of Fingernail is 2 to 2.5. Hence, this value is close to Mohs scale hardness value of Gypsum therefore, gypsum is the correct answer.

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3 years ago

How many orbitals are completely filled

Vlad1618 [11]

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3 years ago

Briefly describe bohr's model postulates and its limitations.

ch4aika [34]

Answer:

Bohr's Model postulates-

I postulate - The electrons in an atom orbit around the nucleus in definite circular paths called orbits or shells.

II Postulate - Each shell or orbit represents a specific amount of energy.

III Postulate - By emitting or absorbing energy, an electron may shift from one stationary energy orbit to another.

Three main Limitations -

1- It adjusts to the hydrogen atom's spectrum but not to the spectra of other atoms.

2 - In the definition of the electron as a tiny particle that spins around the atomic nucleus, the wave properties of the electron are not described.

3- Bohr is unable to understand why classical electromagnetism is inapplicable to his model. That is why, when electrons are in a stationary orbit, they do not emit electromagnetic radiation.

Explanation:

About Bohr's postulates-

1 - The electron spins in circling circles around the nucleus, emitting no energy. The orbital angular momentum is constant in these orbits.

Only certain radii of orbits, corresponding to certain given energy levels, are required for electrons in an atom.

2- Not every orbit is possible. However, whenever an electron is in a legal orbit, it is in a state of unique and constant energy and does not emit energy (stationary energy orbit).

For example - The energies allowed for electrons in the hydrogen atom are given by the following equation: The Rydberg constant for the hydrogen atom is $-2.8\times10^-^1^8$ in this equation, and n = quantum number will range from 1 to ∞. For each of the values of n, the electron energies of a hydrogen atom produced by the above equation are negative. As n rises, the energy becomes less negative and thus rises.

3- By emitting or absorbing energy, an electron may shift from one stationary energy orbit to another.

The energy difference between the two states would be equal to the energy released or consumed. This energy E is in the form of a photon, and it can be measured using the following formula:

$E=h$ $v$

E is the energy (absorbed or emitted) in this equation, and h is the Planck constant (its value is $6.63\times10^-^3^4 Js$ ) and v denotes the frequency of light, which is calculated in 1/ s.