$解：(1) 設\rho ={\frac {k} {V}}$
$∵ 當V=10\ \mathrm {m^3}時，\rho =1.43\ \mathrm {kg/m^3}$
$∴ 1.43={\frac {k} {10}}$
$解得，k=14.3$
$∴ 函數(shù)表達式為\rho ={\frac {14.3} {V}}$
$(2) 當V=2\ \mathrm {m^3}時，\rho ={\frac {14.3} {2}}=7.15(\ \mathrm {kg/m^3})$
$∴ 當V=2\ \mathrm {m^3}時氧氣的密度\rho為7.15\ \mathrm {kg/m^3}$
