Answer:
It is none. Echo is formed when sound waves hit a hard surface.
Explanation:
It is usually measured on the Pauling scale, on which the most electronegative element (fluorine) is assigned an electronegativity of 4.0. Each of these elements has a low electronegativity on the Pauling scale, and the electronegativities clearly decrease down the group.
What we're looking for here is the gas sample's molar mass given its mass, pressure, volume, and temperature. Recalling the gas law, we have

or

where R is <span>0.08206 L atm / mol K, P is the given pressure, T is the temperature, and V is the volume.
Before applying the values given, it is important to make sure that they are to be converted to have consistent units with that of R.
</span>
Thus, we have
P = 736/ 729 = 0.968 atm
T = 28 + 273.15 = 301.15 K
V = 250/1000 = 0.250 L
Now, applying these converted values into the gas law, we have


Given that the mass of the sample is 0.430 g, we have

Thus, the gas sample has a molar mass of 43.9 g/mol.
Atomic number is same as the number of protons in the element which is further equal to the number of electrons. As the number of electrons increases in the element, the atomic number of the element also increases.
In periodic table, elements are arranged in the groups, and these groups are columns starting from 1 to 18, elements are arranged in increasing order of atomic number. Elements are placed with difference of one atomic number.
First four elements present in the periodic table is:
atomic number is one (1).
atomic number is two (2).
atomic number is three (3).
atomic number is four (4).
Thus, the series of atomic numbers that represents the ordering of consecutive elements within the periodic table is the last option - 1, 2, 3, 4...