Which one of the following statements about the refractive index of a material medium with respect to air is correct?
It can be either positive or negative
It can have zero value
It is unity for all materials
It is always greater than one
For election to the Lok Sabha, a nomination paper can be filed by
Miscellaneous · Easy
In a month if the seventh day is three days earlier than Saturday,then the nineteenth day of the month will be a
Miscellaneous · Easy
Which among the following events happened earliest ?
Miscellaneous · Easy
An 80-litre solution of alcohol and water has 75% alcohol. How much water (in litres) must be added to bring down the concentration of alcohol to 60%?
Miscellaneous · Easy