Answer:
A, C, and D
Explanation:
The correct options that apply to the principal conservation of energy are A, C, and D.
A is correct because energy can neither be created nor destroyed. However, energy can be transfered from one location to another or be converted from one form to another. <em>Whether transferred to converted, the magnitude remains the same.</em>
C is correct because energy cannot be destroyed but can be transferred or converted. <em>Hence, if a body or a location loses temprature, then the loss is being gained by another body or location.</em>
D is also correct. A closed system is a system that does not exchange matter with its surroundings. <em>Hence, the total energy remains the same within the system. </em>
<span>Balanced chemial equation:
2NaI(aq)+Hg2(NO3)2(aq) →Hg2 I2 (s) + 2 NaNO3 (aq)
You can see it better if I use latex:

As per the phases this is the interpretation:
The symbols (aq) stands for aquous meaning that the compound is dissolved in water.
The symbol (s) stands for solid, meaning tha the compound precipitate and is not dissolved in water.</span><span>
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Answer:
C-O: polar covalent
Mg-F: ionic
Cl-Cl: nonpolar covalent
Explanation:
Ionic bonds are formed between an atom of a metallic element and another atom of a non-metallic element. Thus, Mg-F is an ionic bond, in which Mg is the metal and F is the nonmetal.
Covalent bonds are formed between two non-metallic elements. So, C-O and Cl-Cl are covalent bonds, because C, O, and Cl are nonmetals.
In C-O, the atom of oxygen (O) has more electronegativity than the atom of carbon (C). Thus, O will attract the electrons with more strength and a difference in charge will be established between the two bonded atoms. So, this covalent bond is polar.
In Cl-Cl, both atoms have the same electronegativity because they are from the same chemical element (Cl). Thus, this bond is nonpolar.
Purple stem plants can be formed by genetics, they use their energy slightly different from other plants, they use less energy, but that may also be because of bad nutrition, and because they may be hungry for nutrients.