(i) Frequency =`2pisqrt(m//k)`
(Frequency is independent of g in spring)
(ii) Initial extension in spring in equilibrium `=(mg)/(k)`
Extension in spring in equilibrium when lift starts accelerating upwards `=(m(g+a))/(k)`
`therefore` Amplitude `=(m(g+a))/(k)-(mg)/(k)=(ma)/(k)`