Answer:
According to the modern periodic law, the properties of the elements and their compounds are a periodic function of their atomic numbers. Thus, in the modern periodic table, atomic number forms the basis of the classification of elements;The modern table is called 'long form' of the periodic table.
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<u>Answer:</u> The product side must be 
<u>Explanation:</u>
Single displacement reaction is defined as the reaction in which more reactive metal displaces a less reactive metal from its chemical reaction.

Metal C is more reactive than metal A.
The reactivity of metal is determined by a series known as reactivity series. The metals lying above in the series are more reactive than the metals which lie below in the series.
Law of conservation of mass states that mass can neither be created nor be destroyed but it can only be transformed from one form to another form. This also means that total number of individual atoms on reactant side must be equal to the total number of individual atoms on the product side.
When zinc metal reacts with hydrochloric acid, it leads to the production of zinc chloride and hydrogen gas. The chemical reaction follows:

<u>On reactant side:</u>
Number of zinc atoms = 1
Number of hydrogen atoms = 2
Number of chlorine atoms = 2
<u>On product side:</u>
Number of zinc atoms = 1
Number of hydrogen atoms = 2
Number of chlorine atoms = 2
Hence, the product side must be 
The problem applies Charles' law since constant pressure with varying volume and temperature are given. Assuming ideal gas law, the equation to be used is

=

. We make sure the temperatures are expressed in Kelvin, hence the given added with 273. The volume 2 is equal to 25.2881 liters.
Because atoms are the small and can't be seen by your eyes. It is so small that scientists need to use a model. A model help scientists study things. So, scientists needs to study atoms using models.
given days = 42 days
So, number of half life, n = 42/14.3 = 2.93
So, after 42 days, the mass of sodium phosphate sample left = original mass
x (1/2)^n,
= 157 mg x (1/2)^2.93 = 20.60 g of Na3PO4 after 42 days
Formula mass of Sodium phosphate = 3(23) + 32 + 4(16) amu = 165 amu
165 g of sodium phosphate contains 32 g of Phosphorus
20.60 g ------------------------------? = 20.60 x 32/ 165 =3.99g of P32