The flash of an exploding cracker is seen even before we hear the sound. Why?

Statement-1 : The flash of lightening is seen before the sound of thunder is heard Statement-2 : The sound of thunder is produced after the flash of lightening.

Assertion: The flash of lightening is sees before the sound of thunder is heard. Reason: Speed of sound is greater than speed of light.

"During thunder, we can hear a rolling sound." Why?

An observer sitting in line of two tanks, watches the flashes of two tanks firing at each other at the same time, but he hears the sounds of two shots 2 s and 3.5 s after seeing the flashes. If distance between the two tanks is 510 m, find the speed of sound.

If we put a cardboard (say 20 cm xx 20 cm) between a light source and our eyes, we can't see the light. But when we put the same cardboard between a sound source and our ear, we hear the sound almost clearly, Explain.

The smoke from the gun barrel is seen 2 second before the explosion is heard. If the speed of sound in air is 340 m s^(-1) , calculate the distance of observer from gun. State the approximation used.

How many of the following statements are CORRECT ? I. India is one of the 12 megadiversity countries of the world. II. India has only 8.1 percent of the worl's land area. III. Nearly 45,000 species of animals and twice as many as plants have been recorded from lndia. IV. According to May's global estimates , only 22 percent of the total species have been recorded so far. v. Nature's biological the library is burning even before we catalogued the titles of all books stocked there.

Read the following statements. ''Nature's biological library is burning even before we catalogued the titles of all the books stocked there'' This statement is given is your NCERT book. What would its mean

Read the following statements. ''Nature's biological library is burning even before we catalogued the titles of all the books stocked there'' This statement is given in your NCERT book. What would its mean