No, it is not.
Center of mass is the point at which the object can be balanced and treating a collection of masses as one mass at their common centre of mass.
Center of gravity is the point from which the force of gravity acts on an object or system.
A deform-able or flexible body is one that can distort. It would normally refer to a solid object so that as it deforms, it sort of deforms in a way that it could return to its starting shape if all the external forces were removed that caused it to deform.
Examples are belt, rope, rubber band etc.
A perfectly inelastic collision occurs when the maximum amount of kinetic energy of a system is lost. In a perfectly inelastic collision, i.e., a zero coefficient of restitution, the colliding particles stick together.
Linear mass density is the amount of mass per unit length.
Just as ordinary density is mass per unit volume, linear density is mass per unit length. Linear densities are usually used for long thin objects such as strings for musical instruments.
Here chain is long and thin, so we have consider linear mass density.
An isolated system is a thermodynamic system that cannot exchange either energy or matter outside the boundaries of the system. Means the energy and the mass content of the system will not change with time.