Questions

The number of protons is equal to the number of electrons. That is the number of positive charges is equal to the number of negative charges.

A respirometer is a device used to measure the rate of respiration of a living organism by measuring its rate of exchange of oxygen and/or carbon dioxide.

The first cellular phone service in india was introduced by Modi Telstra on August 23, 1995 in calcutta under the name Mobile Net. 

Air Pressure can be defined as the pressure of air in the earth's atmosphere. It reaches a maximum of about 100,000 Pa near sea level and decreases as altitude increases.

The barometer is an instrument which is used for measuring Air pressure.

Physics instruments and their uses:

Barkometer  - - - Tanning liquors used in tanning leather

Bolometer  - - - Electromagnetic radiation

Spectrometer - - -  Properties of light.

A restrictive clause is one that limits the meaning of the word it describes.

For example :: 

The girl who lives next door is beautiful.

This restrictive clause limits "the girl" to say it's specifically the one next door.