Helium: It is an inert gas that is lighter than air. It is non-flammable.

The Agni missile is a family of medium to intercontinental range ballistic missiles developed by India, named after one of the five elements of nature. In the Agni series of ballistic missiles, Agni II, Agni III and Agni IV are Intermediate Range Ballistic Missiles (IRBMs). These are all nuclear weapons capable surface to surface ballistic missile.

A pacemaker is a medical device used to regulate the heartbeat in individuals with abnormal heart rhythms (arrhythmias). It is often implanted in the chest to help control the heart's rhythm and treat conditions like bradycardia (slow heart rate) or other rhythm disorders. Pacemakers are typically prescribed by cardiologists, specialized doctors who diagnose and treat heart-related conditions. The decision to implant a pacemaker is made by a healthcare provider based on the patient's specific medical condition and needs.

Tissues are formed from the assemblage of cells and intercellular materials in various proportions in which one component predominates. In nervous tissue as an example, nerve cells predominate while in connective tissues such as Ligaments and Tendons, intercellular fibrous materials predominate.