Answer: Elements in Group 2
Explanation: The periodic table was arranged by Dmitri Mendeleev specifically around similarites in their chemical behaviors. He found that as atomic number increases, at some point an element starts to react in a manner similar to a previous one. When that happened, he would place the larger element under the smaller one, and eventually noticed a periodicity in the table. Elements in a column (Groups) had similiar chemical properties. We know today that these similarities are due to the electron configuration, and that these configurations repeat themselves. He left gaps in the table when he could find an existing element with properties similar to others in that group. I big leap of faith, but it worked. Elements for those missing boxes were eventually discovered.
The given alkyne is Option A 3-heptyne
<h3>
What is an Alkyne ?</h3>
The hydrocarbon having at least one C-C triple bond is called an Alkyne.
It has the general formula of 
.
In the question it is being mentioned that it is an alkyne so there will be a triple bond and not a double bond.
It has been asked in the question that
CH3CH₂C ≡ CCH₂CH₂CH3 is which alkyne from the given option.
The counting of the Carbon chain is done from the left side and the Triple bond is at the 3rd Carbon , so 3-heptyne .
To know more about Alkyne
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The volume of water he dissolved the solute is 250 cubic centimeter.
<u>Explanation</u>:
Concentration = mass of solute in g / volume in dm^3
The concentration of a solution is defined as the ratio of mass of solute in grams to the volume of water in dm^3.
If concentration of a solution = 8 g/dm^3.
mass of solute =2 g.
Volume of a water = 2 / 8 = 0.25 dm^3. (or) 250 cubic centimeter.
The number of protons in one atom of an element determines the atom's identity, and the number of electrons determines its electrical charge. The atomic number tells you the number of protons in one atom of an element. ... The atomic mass of an element is the total number of protons and neutrons in the nucleus of the atom.
