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(a)   - block elements begin to appear in period 4 and they are called transition metals

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The energy level that filled with (18) electrons is (a)  

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(a)   are different forms of the same element's atoms that have the same atomic number but differ in mass number

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Number of (a)   = Mass number - Atomic number

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The symbol of copper atom is -------------

(a)  

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In the potassium ( K ) mass number = 39 , atomic number 19 then :

No. of electrons = (a)  

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(a)   imaginary places around the nucleus in which the electrons move according to their energy

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Negatively charged particles of negligible mass and revolve around the nucleus at a very high speed

(a)  

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In this figure

Then atom ( ( Active or inactive ) (a)  

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(a)   is the sum of protons and neutrons number found in the nucleus

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Nitrogen element in NPK Fertilizer is essential for the greening of plant (a)  

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Number of negative electrons (a)   Number of positive protons

then the atom is neutrally electrically charge

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In the fourth energy level (N) = 2n² = (a)   electrons

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(a)   is The last energy levels and highest energy

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Sodium is locate in the (a)   group

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Group 7A called with (a)   non_metals group

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(a)   is the firest scientist proposed the first scientific theory.

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The (a)   contain 1 or 2 or 3 electrons in outer shell

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(a)   is the symbol of iron