Substance which is weakly repelled by a magnetic field is

Options

A. `a) O_(2)`
B. b) `H_(2)O`
C. c) `CrO_(2)`
D. d) `Fe_(3)O_(4)`

Answer

B

Explanation

`O_(2)` molecule is paramagnetic and the presence of two unpaired electrons in the `overset("*")(pi)(2p_(x)) or overset("*")(pi)(2p_(y))` molecular orbitals accounts for its paramagnetic nature. Similary in `CrO_(2), Fe_(3)O_(4) and ZnFe_(2)O_(4)`, the d-orbitals of transition elements are not ful-filled and have unpaired electrons and hence, are paramagnetic. Whereas, `H_(2)O` is diamagnetic because of the presence of all paired electrons and hence repelled by magnetic field.