Questions

A search engines are a software systems used for searching about any information in the world on the web.

Search engines like Google, Bing, Internet explorer, Yahoo, etc... functions by providing relevant search results for the keywords user searches. 

Hence, the given statement is TRUE.

All living cells arise from pre-existing cells is one component of the cell theory.

The Cell Theory is one of the basic principles of biology.

The Cell Theory states:

1. All living organisms are composed of cells. They may be unicellular or multicellular.

2. The cell is the basic unit of life.

3. Cells arise from pre-existing cells.

Saliva is produced by the salivary gland which helps in food digestion.

Option A) contains fluoride to harden the tooth enamel is not the function of saliva.

Radioactive decay is likely to occur when the nuclei of an atom doesn't have enough binding energy to hold the nucleus together due to excess of rotons or nutrons in it.

ICMP means Internet Control Message Protocol and is always coupled with the IP protocol (There are 2 ICMP variants one for IPv4 and one for IPv6.) echo request and echo response are the two operation codes of ICMP used to implement ping.