Rulers are used to measure lengths/distances.
This depends on what you are measuring. A tool that can be used is a tape measure.
A protractor is the common tool used in mathematics for measuring and drawing angles.
A balance is the best tool for measuring mass.
a tripel-beam-balance
The answer depends on what characteristic the tool is used to measure.
Cylinder
A hygrometer.
A tool that is used for measuring small amount of liquid is a graduated cylinder.
A measuring rod or tape.
A clock or stop watch
A scale.
A caliper.