(A) Radio Detecting and Ranging

(B)Region Device and Ranging

(C) Radio Detect and Rangs

(D) Radio Device and Ranging

(A) a wave reflects upon itself

(B) the amplitude of a wave exceeds its wavelength

(C) two waves overlap

(D) the speed of the wave is zero or near zero

(A)  frequency

(B) intensity

(C) number of overtones

(D)none of these

A) frequency increases and speed decreases

B) frequency is the same but the wavelength is smaller in water than in air

C) frequency is same but the wavelength is larger in water than in air

D) frequency and speed both decreases

(A) volume of rainfall

(B) cloud volume and speed

(C) salinity of sea

(D) all options are correct

(A)  rectilinear propagation of light

(B) reflection

(C) refraction

(D) total internal reflection

(A) Democritus

(B) Proust

(C) Lavoisier

(D) John Dalton

(A) south

(B) north

(C) east

(D) west

(A) gravitational pull

(B) rotation of earth

(C) revolution of earth

(D) uneven heating of earth

(A) activator

(B) fuse

(C) explosive

(D) power source