Particles stay the same unless there is a chemical change whether the matter is solid, liquid or gas. ... When substances change state there is no change in mass so if 100 g of ice is melted 100g of water are formed this will boil to form 100g of steam (this is called "conservation of mass").
Answer:

F » magnetic force
B » magnetic flux density
l » length / circumference

r » radius

Answer:
4.3 N/m
Explanation:
m = 230 g = 0.230 kg, x = 8.2 cm
in 13 oscillations, time taken = 19 s
In 1 oscillation, time taken = 19 / 13 = 1.46 s
By the use of formula of time period , Let k be the spring constant.


0.054 = 0.230 / k
k = 4.26 N/m
k = 4.3 N/m