Fluorite is harder than gypsum but softer than apatite. Thus, the correct option is B.
<h3>What is the hardness of any element?</h3>
The hardness of any element may be defined as the capability of a material to oppose the process of deformation and remains in actual shape precisely.
According to the table of hardness scales by Mohs, the increasing order of given hardness of given elements is as follows:
Gypsum < Fluorite < Apatite.
Therefore, Fluorite is harder than gypsum but softer than apatite. Thus, the correct option is B.
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D. Cycloalkene
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<span>The symbol on a line that indicates a cold front on a map is a triangle. The point of the triangle will indicate the direction of movement of the cold front.</span>
The angular momentum of an electron in the third Bohr orbit of a hydrogen atom is given by mvr=3h÷2π
<h3>What is momentum?</h3>
Momentum is defined as the amount of motion occurring in something that is moving, or the force that drives something forward to keep it moving.
Bohr never assumed stable electronic orbits with the electronic angular momentum quantized as
l=mvr = 
Quantization of angular momentum means that the radius of the orbit and the energy will be quantized as well.
Bohr assumed that the discrete lines seen in the spectrum of the hydrogen atom were due to transitions of an electron from one allowed orbit/energy to another.
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Answer: 10 electrons
Explanation:
N represents Nitrogen. Nitrogen has an atomic number of 7, this means in ground state it has 7 electrons also.
But N-3, means Nitrogen has gained 3 more electrons. So, we have 10 electrons