19.
Audio cassettes are coated with which oxide?
Answer : D. iron
20.
Transfer of heat by molecular collision is
Answer : B. conduction
21.
Colour formation in the films is due to
Answer : C. Interference
22.
The one used in the preparation of lenses and prisms
Answer : B. Flint glass
23.
Name the organism which flies with the help of ultrasonics?
Answer : B. bat
24.
Which of the following regulates and controls the entry of light into human eye?
Answer : B. iris
