Questions

Hubs are specified or operate at Layer1 i.e, the physical layer in the OSI model. Hubs regenerate electrical signals. A hub sends data packets (frames) to all devices on a network, regardless of any MAC addresses contained in the data packet.

Wular Lake is the largest fresh water lake in India. It is sited in Bandipora district in the Indian state of Jammu and Kashmir. The lake basin was formed as a result of tectonic activity and is fed by the Jhelum River.

CPU speed is measured with the processors speed which is measured in MIPS (Million Instructions Per Second), Flops (Floating-point operations per second) and CPU clock speed (usually measured in gigahertz). 

They both are used to replace characters in a string

A food chain is the only chain we can eat.

The alphabetical value of the letters in the left hand column follows through the sequence of Prime Numbers, with the letters in the right hand column representing the corresponding reverse alphabetical values. So,

M = Reverse of M = N.