Olympiad/HOTS corner

The given part of the modern periodic table shows positions of elements $a$ to $j$.

Fill in the blanks by choosing an appropriate option.

Element $\left(\mathrm{i}\right)$ _____ resembles sodium in properties and element $\left(\mathrm{ii}\right)$ _____ belongs to the same group as nitrogen. The formula of the hydride of $g$ is $\left(\mathrm{iii}\right)$ _____. The formula of the compound formed between $b$ and $c$ is $\left(\mathrm{iv}\right)$ _____ while the formula of compound formed between $e$ and $g$ is $\left(\mathrm{v}\right)$ _____.

The elements $\mathrm{A}, \mathrm{B}, \mathrm{C},$ and $\mathrm{D}$ have atomic numbers $4, 12, 17,$ and $19$ respectively. Which pair of elements belongs to the same period?

Which of the following metals is not placed in the eighth group of Mendeleev periodic table?

The atoms having the bigger size among each of the following pairs are 

$\mathrm{i}. \mathrm{Mg}\left(12\right)$ or $\mathrm{Cl}\left(17\right)$

$\mathrm{ii}. \mathrm{Na}\left(11\right)$ or $\mathrm{K}\left(19\right)$

Which of the following elements lose electrons most easily?

Example of Dobereiner's triads is:

The given table shows a part of the periodic table.

$\mathrm{P}, \mathrm{Q}, \mathrm{R}, \mathrm{T},$ and $\mathrm{U}$ are respectively:

The element $\mathrm{X}$ belongs to group $\mathrm{II}$ and period $\mathrm{III}$ of the periodic table. The chemical formulae of its nitrate, sulphate, and phosphate respectively will be