Which of the following is existing oxoacid of fluorine?

Which of the following compounds is formed when ether is dissolved in cold concentrated sulphuric acid?

Calculate the work done in joule if 1 mole of ideal gas is compressed from $25 \mathrm{dm}^3$ to $13 \mathrm{dm}^3$ at constant external pressure 4 bar.

Calculate the edge length of unit cell if a metal with atomic radius 128 pm forming fcc unit cell structure.