Question

a single unit of chemical substance is called as dash​

Answer 1

Answer: The words ‘of substance' may be replaced by the specification of the entity.  

Example When the amount of O2 is equal to 3 moles, n(O2) = 3 mol, then the  

amount of ½O2 is equal to 6 moles, n(½O2) = 6 mol.  

Thus n(½O2) = 2n(O2).  

(2) The definition applies to entities B which should always be indicated by a subscript or in  

parentheses, e.g. nB of n(B).  

(3) A formula unit is not a unit but an entity specified as a group of atoms by the way the  

chemical formula is written.  

(4) mu is equal to the unified atomic mass unit, with symbol u, i.e. mu = 1 u. In biochemistry  

this unit is called the dalton, with symbol Da, although the name and symbol have not  

been approved by CGPM.  

(5) The definition applies to pure substance, where m is the total mass and V is the total  

volume. However, corresponding quantities may also be defined for a mixture as m/n

and V/n, where n = ∑

i

ni . These quantities are called the mean molar mass and the mean  

molar volume respectively.

Answer 2

Answer:

chemistry. Molecule, a group of two or more atoms that form the smallest identifiable unit into which a pure substance can be divided and still retain the composition and chemical properties of that substance.

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