Questions

An invention that improved safety for railway passengers is Air brakes. With the use of air brakes using compressed air, become more effective by preventing many train accidents.

A 40% solution of Formaldehyde known as Formalin is used in the preservation of biological specimens because of its hardening action on proteins. 

India was one of the main centres of world trade and industry. Peter the Great of Russia was led to exclaim: “Bear in mind that the commerce of India is the commerce of the world and ... he who can exclusively command it is the dictator of Europe.”

The American noncommissioned officer tradition began with creation of the Continental Army in 1775 at the beginning of the American Revolution. They adopted NCO traditions from French NCO.

The shortest gestation period known is 12 to 13 days, shared by three marsupials: the American or Virginian opossum (Didelphis marsupialis); the rare water opossum, or yapok (Chironectes minimus) of central and northern South America; and the eastern native cat (Dasyurus viverrinus) of Australia.

Gestation is the period of time between fertilization and birth in oviparous animals.

The elephant has the longest gestation period of about 23 months of any land animal.

Free memory is maintained in linked lists, each of equal sized blocks. Any such block is of size 2^k. When some memory is required by a process, the block size of next higher order is chosen, and broken into two. Note that the two such pieces differ in address only in their kth bit. Such pieces are called buddies. When any used block is freed, the OS checks to see if its buddy is also free. If so, it is rejoined, and put into the original free-block linked-list.