Answer is: A. covalent bonds.
Insulator most likely has covalent bonds, because it must have low electrical conductivity.
1) Substances with covalent bond not conduct an electric current in liquid and solid state, because they not have free ions or electrons.
2) Substances with ionic bond conduct an electric current in liquid, but not in solid state, because in liquids ions are mobile, contrary to solids where ions are fixed.
3) Substances with metallic bond conduct an electric current in liquid and solid state, because they have mobile electrons.
Answer:

Explanation:
Hello,
In this case, the dissociation reaction is:

For which the equilibrium expression is:
![Ksp=[Pb^{2+}][I^-]^2](https://tex.z-dn.net/?f=Ksp%3D%5BPb%5E%7B2%2B%7D%5D%5BI%5E-%5D%5E2)
Thus, since the saturated solution is 0.064g/100 mL at 20 °C we need to compute the molar solubility by using its molar mass (461.2 g/mol)

In such a way, since the mole ratio between lead (II) iodide to lead (II) and iodide ions is 1:1 and 1:2 respectively, the concentration of each ion turns out:
![[Pb^{2+}]=1.39x10^{-3}M](https://tex.z-dn.net/?f=%5BPb%5E%7B2%2B%7D%5D%3D1.39x10%5E%7B-3%7DM)
![[I^-]=1.39x10^{-3}M*2=2.78x10^{-3}M](https://tex.z-dn.net/?f=%5BI%5E-%5D%3D1.39x10%5E%7B-3%7DM%2A2%3D2.78x10%5E%7B-3%7DM)
Thereby, the solubility product results:

Regards.
The Copernican revolution is about the model of the solar system and was given by a polish astronomer. Option C. The discovery that the universe was expanding.
The Copernican Revolution become the paradigm shift from the Ptolemaic model of the heavens, which described the cosmos as having Earth stationery on the center of the universe, to the heliocentric version with the solar on the center of the solar system.
Copernican Revolution, shift the subject of astronomy from a geocentric understanding of the universe, focused around Earth, to heliocentric knowledge, concentrated across the sun, as articulated by the Polish astronomer Nicolaus Copernicus.
This revolution changed the way of thinking of the solar system. Earlier it was thought that earth is in the center of the solar sysytem,i.e; people believed in the geocentric model, but according to Copernicus the solar system has the sun at the center and the remaining planets revolve around it i.e he believed in a heliocentric model.
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The continuous cycling of carbon in the earyh is known as the carbon cycle.
<h3>What is the carbon cycle?</h3>
The carbon cycle is a cycle which explains the various processes by which carbon is recycled between the atmosphere and the earth.
The constant flow of carbon on earth through organisms and the air is known as the carbon cycle. Plants absorb carbon from the atmosphere in the form of carbon dioxide. They use it for respiration and food production.
Animals consume plants, transferring carbon along the food chain.
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Carbon enters back into the atmosphere in the form of carbondio dioxide.
Therefore, the continuous cycling of carbon in the earth is known as the carbon cycle.
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I think the mass the mass was less than the original because a gas was released into the atmosphere. The mass in a chemical reaction is constant in a closed system according to conservation of mass law. However, if a chemical reaction is completed in an open system, mas changes may occur. In our case i think the change in mass was due to the release of hydrogen gas from the reaction to the atmosphere.