Which of the following pairs of d-orbitals will have electron density along the axis ?

Hot concentrated sulphuric acid is a moderately strong oxidizing agent. Which of the following reactions does not show oxidizing behaviour ?

In context with beryllium, which one of the following statements is incorrect ?

Which of the following pairs of ions is isoelectronic and isostructural ?

Which of the following fluoro-compounds is most likely to behave as a Lewis base ?