Questions

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.

Multiple users can't share a local temporary table

Secondary pollutants include ozone, which is formed when hydrocarbons (HC) and nitrogen oxides (NOx) combine in the presence of sunlight.

Whereas Primary pollutant are those pollutants that are directly emitted from their sources, like CO2, CO, SO2 as these gases are directly emitted form burning of fossil fuels.

Acid rain, which is formed when sulfur dioxide or nitrogen oxides react with water, sulfuric acid etc.

Hence, Acidrain is a secondary air pollutant.

Enzymes play an essential role in each living cell of our body. Enzymes are globular proteins that control biological reactions. These are of two types.

1. Intracellular enzymes

2. Extracellular enzymes

Intracellular enzymes are found inside the cell.

Extracellular enzymes act outside the cell.

Enzymes are produced by exocrine glands.

Digestive enzymes of diverse specificities are secreted by the salivary glands, stomach, pancreas, and the small intestine.