Living things included are organisms like animals, plants, bacteria and insects, as well as nonliving components like rocks, soil, sunlight and water.
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A reaction in which heat is evolved is an exothermic reaction while a reaction in which heat is absorbed is an endothermic reaction.
In the first case; Na2CO3 + H2SO4, we can see that this is an acid - base reaction therefore it is a neutralization reaction. Since the tube was hot after reaction, heat is given off so it is exothermic.
In the second case; NaOH + H2SO4, we can see that this is an acid - base reaction therefore it is a neutralization reaction. We are told that the tube is not hot but we don't know the initial temperature of the tube or if it was colder than it's initial temperature so we can not make any inference regarding whether the reaction is endothermic or exothermic.
Lastly, the reaction, NaCl + HC2H5OH does not occur so we mark "no reaction". We are told that the tube is not hot but we don't know the initial temperature of the tube or if it was colder than it's initial temperature so we can not make any inference regarding whether the reaction is endothermic or exothermic.
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Answer:
c, atoms
Explanation:
Molecules are made up of atoms that are held together by chemical bonds. These bonds form as a result of the sharing or exchange of electrons among atoms. The atoms of certain elements readily bond with other atoms to form molecules. Examples of such elements are oxygen and chlorine.
(please answer my question :( )
Answer: density =3.377g/cm³
Explanation:
Density =( molecular weight × effective number of atoms per unit cell) / (volume of unit cell × avogadro constant)
D= (M ×n) /(V×A)
M= 137g/mol
n= 2 (For BCC)
V=a³ , where a= 4r/√3
a= (4×222)/√3
a=512.69pm
a= 512.69×10^-10cm
V= ( 512.69×10^-10)^3
V= 1.3476×10^-22cm³
D= (137×2)/(1.3476×10^-22 × 6.02^23)
D= 3.377g/cm³
Therefore the density of barium is 3.377g/cm³
Au2S is =<u><em> 426 g/mol</em></u> for molar mass
