a boat is moving downstream in a river. the river is flowing with a constant speed. at a certain point 'a' boat crosses free floating bouy . after this point a boat keeps moving for 1hr. and then turns around . it crosses the bouy again at a point b . if distance between point a and b is 3 km. find the speed of the river.

What type of questions asked from the lesson of magnetic effect of electric current 

Wavelength of green light is

A) 400-450 nm

B) 500-550 nm

C) 660-720 nm

D) 720-800 nm

What is the difference between anaerobic & aerobic respiration? Name some organism that uses the aerobic mode of respiration?

What are the main components of our environment? Explain each of them briefly.

What are examples of hydrotropism plants?