Is mass conserved in chemical reactions?

Mass is not conserved in chemical reactions. The fundamental conservation law of the universe is the conservation of mass-energy. This means that the total mass and energy before a reaction in a closed system equals the total mass and energy after the reaction. According to Einstein's famous equation, E = mc2, mass can be transformed into energy and energy can be transformed into mass. This is not some exotic process, but in fact happens every time there is a reaction. Mass is therefore never conserved because a little of it turns into energy (or a little energy turns into mass) in every reaction.

the three components of a nucleotide are the nitrogenous base, the phosphate group and the five-carbon sugar.

igneous rocks are formed by solidification of cooled magma (molten rock), with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks.  

the composition depends on the source magma. there are almost a thousand types of composition found till now.  

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