A silver article generally turns black when kept in the open for a few days. The article when rubbed with toothpaste again started shining. Name the black substance formed and give its chemical formula (A) Silver oxide, (Ag2O) (B) Silver chloride, (AgCl) (C) Silver sulphide, (Ag2S) (D) Silver iodide, (AgI)

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?