1. Ultrasound refers to frequency of sound a. Higher than 10 MHZ b. Lower than 20 HZ c. Higher than 20 kHZ d. Lower than 20 kHZ 2. Speed of sound depends on a. Medium density only b. Medium porosity and density c. Medium compressibility and porosity d. Medium density and compressibility 3. What is the maximum use temperature of Iron-Constantan? a. Greater than 1200 C but less than 1300 C. b. Greater than 800 C but less than 1000C. c. Greater than 1600 C. d. 800 C. 4. While using a measuring instrument it is essential to ensure- a. Precision only b. Accuracy only c. Precision but not accuracy d. Both precision and accuracy