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.
To learn more about the Hardness of elements, refer to the link:
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Is a gas in the greenhouse that absorbs and emits radiation within the thermal infrared range.
Unit ppm stands for parts per million. in terms of mass, ppm is equivalent to mg/kg.
since 1 kg is 10⁻⁶ mg, 1 kg is equivalent to million mg.
therefore mg/kg is also ppm.
there are 1.3 g of Ca ions in 3100 kg
if 3100 kg contains - 1.3 g of Ca
then 1 kg contains - 1.3 g / 3100 kg
then Ca ions - 0.42 x 10⁻³ g/kg
Ca ion concentration - 0.42 mg/kg
therefore Ca ion concentration is 0.42 ppm
Answer:
5.45*10⁻⁴ moles of silane gas (SiH₄) are present in 8.68 mL measured at 18°C and 1.50 atm.
Explanation:
An ideal gas is a theoretical gas that is considered to be composed of point particles that move randomly and do not interact with each other. Gases in general are ideal when they are at high temperatures and low pressures.
An ideal gas is characterized by three state variables: absolute pressure (P), volume (V), and absolute temperature (T). The relationship between them constitutes the ideal gas law, an equation that relates the three variables if the amount of substance, number of moles n, remains constant and where R is the molar constant of the gases:
P * V = n * R * T
In this case:
- P= 1.5 atm
- V= 8.68 mL= 0.00868 L (being 1000 mL= 1 L)
- n= ?
- R= 0.082

- T= 18 C= 291 K (being 0 C= 273 K)
Replacing:
1.5 atm* 0.00868 L= n* 0.082
*291 K
Solving:

n= 5.45*10⁻⁴ moles
<u><em>5.45*10⁻⁴ moles of silane gas (SiH₄) are present in 8.68 mL measured at 18°C and 1.50 atm.</em></u>