10. When a ray of sunlight enters a dark room , its straight path become visible because of dust particles hanging in the air. It is because light is :
a) Visible
B) Transparent
c) Invisible
d) opaque
e) None of these
11. A six feet tall lady wants to see her full image in a plane mirror . The minimum length of the mirror will be :
a) 6 feet
b) 12 feet
c) 4 feet
d) 3 feet
e) None of these
12. The principle used in radar is the same as that of Sonar. In radar we use radio waves ; whereas in sonar we use :
A) red waves
b) Infrared waves
c) Ultrasonic
d) super sonic
e) None of these
13. In a fission nuclear reaction , a heavy nucleus breaks up into smaller nuclei whereas in another nuclear reaction two or more than two possibly nuclei are fused to form a heavy nucleus This nuclear reaction is called :
a) Chemical Reaction
b) Nuclear reaction
c) Fission nuclear reaction
d) Fusion nuclear reaction
e) None of these