The correct answer is C. 1, 2 and 3.
Piezoelectric materials are those that generate an electric charge when they are subjected to mechanical stress, or that change shape when an electric field is applied to them. Barium titanate, lead titanate, and lead zirconate are all piezoelectric materials. Cadmium sulfate is not a piezoelectric material.
Barium titanate is a ceramic material that is used in a variety of applications, including piezoelectric sensors, actuators, and filters. It is a ferroelectric material, which means that it has a permanent electric polarization. When an electric field is applied to barium titanate, the polarization changes, which causes the material to change shape. This property is used in piezoelectric sensors to detect mechanical stress or vibration. Barium titanate is also used in piezoelectric actuators to create motion.
Lead titanate is another ceramic material that is used in piezoelectric applications. It is similar to barium titanate, but it has a higher Curie temperature, which means that it can be used in applications where higher temperatures are required. Lead titanate is used in piezoelectric sensors, actuators, and filters.
Lead zirconate is a ceramic material that is used in piezoelectric applications. It is similar to barium titanate and lead titanate, but it has a higher mechanical strength. Lead zirconate is used in piezoelectric sensors, actuators, and filters.
Cadmium sulfate is a salt that is used in a variety of applications, including batteries, pigments, and stabilizers. It is not a piezoelectric material.