Questions

Tooth Enamel is the hardest and most highly mineralized substance in the human body. It is a tissue and not a bone. This tissue has high mineral content which makes it hardest substance.

Femur and Temporal bone of the skull are the hardest bones of the human body.

When a thread is created the threads does not require any new resources to execute the thread shares the resources like memory of the process to which they belong to. The benefit of code sharing is that it allows an application to have several different threads of activity all within the same address space. Whereas if a new process creation is very heavyweight because it always requires new address space to be created and even if they share the memory then the inter process communication is expensive when compared to the communication between the threads.

It is the friction between the feet and the ground that helps us to walk. Without this friction we would slip and fall

The Surface tension pulls the surface of the drop equally at all points thus produces the spherical shape having the minimum surface area. This surface tension is the "skin" of a body of water that makes the molecules stick together.