The symbol : 
<h3>Further explanation
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There are two components that accompany an element, the mass number and atomic number
Atoms are composed of 3 types of basic particles (subatomic particles): <em>protons, electrons, and neutrons
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The Atomic Number (Z) indicates the number of protons and electrons in an atom of an element.
Atomic number = number of protons = number of electrons ⇒ neutral number
Atomic mass is the sum of protons and neutrons
Atomic Number (Z) = Atomic mass (A) - Number of Neutrons
The element has 71 electrons and a charge of +1 , so
Number of protons = 71 + 1 = 72
Number of protons = the atomic number = 72
The element with atomic number 72 is Hafnium(Hf)
The atomic mass of Hf = 178 g/mol
Answer:
The sales clerk can count your nails in 6 groups of 500 nails, or 30 groups of 100 nails to ease the counting process and garauntee a more accurate result.
Explanation:
A Glacier is a large area of thick ice that moves slowly
Example of correct chemical formula is Al2O3
Explanation
Al2O3 is correct because Aluminium (Al) has a valence of three(3) while oxygen(O) has a valence of two (2) . when writing a chemical formula one start with cation(POSITIVELY CHARGED) symbol followed by anion symbol (negatively charged). The valence number are interchanged between cation and anion and are then written as subscript.
Molecular weight of (NH4)2 CO3 = 96 gm. 96 gm (NH4)2CO3 = 1 mol of (NH4)2CO3 = 2 moles of NH4.
Therefore 1.3 gm of (NH4)2CO3 = 1.3x2/ 96 = 0.027 moles.
