Correct Answer - A::B::C
`T=2pisqrt((m_(1)+m_(2))/(K))`
`=2pi sqrt((6)/(2400))=(pi)/(10)`
`rArr f=(10)/(pi)`
Instantaneous tension just after `m_(2)` is released will be zero as the spring is unstressed.
Amplitude of `m_(1)=m_(2)g//K=25//12 cm`, hence maximum displacement of `m_(1) ` will be `25//6 cm`.