The atomic number of an element is 19. (a) Write the electronic configuration of the element and determine (i) the valency of the element and (ii) whether the element is a metal or non-metal. (b) Write the formula of the oxide of the element. (c) Is the element more reactive or less reactive than Na (atomic number 11). Justify your answer giving example.

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?