Name the equipment used in measuring thermal behaviour of water

Which of the following equipments is used to study thermal behaviour of water?

Name the compound used for measuring the hardness of water, i.e., for estimation of Ca^(2+) and Mg^(2+) ions.

Name the compound used for measuring the hardness of water, i.e., for estimation of Ca^(2+) and Mg^(2+) ions.

Name the unit used for measuring the sound level.

Name the equipment used to measure rate of growth of short length plant.

Name the instrument used to measure the optical activity of a substance.