In which one of the following arrangements the given sequence is not strictly according to the properties indicated against it
CO2 < SiO2 < SnO2 < PbO2 :Increasing oxidizing power
HF < HCl< HBr < HI:Increasing acidic strength
H2O < H2S< H2Se < H2Te:Increasing pKa values
NH3 < PH3< AsH3 < SbH3:Increasing acidic character
The correct answer is option (C) : H2O < H2S< H2Se < H2Te:Increasing pKa values
Given below are two statements. 
In the light of the above statements, choose the correct answer from the options given below:
Given below are two statements:
Statement I: Nitrogen forms oxides with +1 to +5 oxidation states due to the formation of $\mathrm{p} \pi-\mathrm{p} \pi$ bond with oxygen.
Statement II: Nitrogen does not form halides with +5 oxidation state due to the absence of d-orbital in it.
In the light of the above statements, choose the correct answer from the options given below:
Given below are the pairs of group 13 elements showing their relation in terms of atomic radius. $(\mathrm{B}<\mathrm{Al}),(\mathrm{Al}<\mathrm{Ga}),(\mathrm{Ga}<\mathrm{In})$ and $(\mathrm{In}<\mathrm{Tl})$ Identify the elements present in the incorrect pair and in that pair find out the element (X) that has higher ionic radius $\left(\mathrm{M}^{3+}\right)$ than the other one. The atomic number of the element (X) is

The group 16 elements (oxygen group elements) of the periodic classification are also known as chalcogens because most of the copper ores have copper in the form of oxides and sulphides. The word chalcogen means “ore formation” which is derived from the Greek word “Chalcos” (Ore) and “gen” (formation).
There are 5 elements that come under Group 16 of the Modern Periodic Table namely:
The general electronic configuration of the chalcogens can be written as ‘ns2np4’, where ‘n’ denotes the value of the principal quantum number corresponding to the valence shell of the element.

The electron configuration of the synthetic element livermorium (believed to be a chalcogen) is predicted to be [Rn]5f146d107s27p4.