Answer:- b. +3
Explanations:- Charge of a metal ion is equal to the number of valence electrons it has as it loses these electrons to have its nearest noble gas like electron configuration.
Al has 3 valence electrons and being a metal it loses all of these and so the charge of Al ion is +3. It could be shown as:

So, the right choice is b. 3+.
The answer is B Nitrogen atoms will form three covalent bonds (also called triple covalent) between two atoms of nitrogen because each nitrogen atom needs three electrons to fill its outermost shell. Another example of a nonpolar covalent bond is found in the methane (CH4) molecule.
It would be most likely to be found in carbohydrates
Try c I think is the most accurate one
<span>Answer: option (3) energy, charge and mass.
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<span>Explanation:
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<span>1) The conservation of energy is a universal principle: energy is neither created nor destroyed. This is the first law of thermodynamic.
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<span>2) Mass conservation is another universal principle: mass is neither created nor destroyed. This principle is the base of the stochiometry: thas mass of the reactans equal the mass of the products. Another consequence, since the atoms are not transformed in the chemical reactions, is that the number of each kind of atoms in the reactants equal the number of the same kind of atoms in the products.
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<span>3) The third principle is the conservation of charge. Also, charge is neither created nor destroyed. The electrons gained/lost by one species are lost/gained by other species. So, when one atom or molecule is oxidized other is reduced.</span>