Which among the following is the most appropriate and correct practise from the point of view of healthy environment?

Which one of the following metals are prominently used in mobile phone batteries?

An electron and a proton are circulating with the same speed in circular paths of equal radius.Which one among the following will happen,if mass of  a proton is 2000 times that of the electron?

In the absence of cold labrador current,which of the following would happen

Seismic gaps are

Which one of the following diseases in humans can spread through air?