Question

a block of a material of volume 20cmand density 2.5cm is suspended frm a spring balance wit half of the vol of the block immersed in a water,what is the reading of a spring balance?

Answer 1

vol = 20 cm^3 ?????
Your typing is very confusing

then upward force = weight of water displaced (Archimedes)
= 10 cm^3 * 1 gram/cm3 * g = 10 grams * g = .010 kg * 9.81 = .098 Newtons upward buoyancy

but
weight = volume * density * g
= 20 * 2.5 * 9.81/1000 = 0.49 N

difference = spring force = 0.39 N

Answer 2

the solving is not correct