Questions

p type of semiconductor is obtained when Silicon is doped with a trivalent impurity like Aluminium. Aluminium is a p-type dopant, which means that when a semiconductor i.e. silicon is doped with aluminium, it creates a hole (positively charged carrier) by accepting an electron from the silicon atom. Electrical conductivity of semiconductors increasesand resistivity remains the same

Echolocation is an adaptation bats use to hunt insects in flight, locate flowering plants and find warm places for hibernation.

Database provides necessary means to achieve this abstraction. By structure of a database we mean the data types, relations, and constraints that should hold on the data.

Packet filter is a standard router equipped with some extra functionality. The extra functionality allows every incoming or outgoing packet to be inspected. Packets meeting some criterion are forwarded normally. Those that fail the test are dropped

Nucleus serves as the control center for cell metabolism and reproduction.

A Dice has 6 faces with 1 - 6 number of dots one on each side.

So in total 1 + 2 + 3 + 4 + 5 + 6 = 21 dots resembles as eyes.