The total number of monohalogenated organic products in the following (including stereoisomers) reaction is ______.

An element with molar mass 2.7 $$ \times $$ 10^-2 kg mol^-1 forms a cubic unit cell with edge length 405 pm. If its density is 2.7 $$ \times $$ 10³ kg m^-3, the radius of the element is approximately ______ $$ \times $$ 10^-12 m (to the nearest integer).

The photoelectric current from Na (Work function, w₀ = 2.3 eV) is stopped by the output voltage of the cell
Pt(s) | H₂ (g, 1 Bar) | HCl (aq., pH =1) | AgCl(s) | Ag(s).
The pH of aq. HCl required to stop the photoelectric current form K(w₀ = 2.25 eV), all other conditions remaining the same, is _______ $$ \times $$ 10^-2 (to the nearest integer).

Given, 2.303$${{RT} \over F}$$ = 0.06 V;
$$E_{AgCl|Ag|C{l^ - }}^0$$ = 0.22 V

A dice is thrown two times and the sum of the scores appearing on the die is observed to be a multiple of 4. Then the conditional probability that the score 4 has appeared atleast once is :