Choose the letter of the correct answer. Write your answers on a separate sheet of paper. 1. Which of the following is essential in order for us to see things A. electricity C. light B. heat D. sound 2. Which of the following statements is TRUE ? A. Sound cannot travel through air. B. Light always travels in a straight line. C. Sound travels faster in air than in solids. D. Heat transfer through liquid is known as radiation. 3. By what process does heat travel from the sun to Earth? A. Heat is radiated through space. B. Heat travels through wind. C. Heat is conducted through air molecules. D. Convection of heat through air currents. 4. Which of the following indicates the amount of heat present matter?