Questions

The seven elements — helium, neon, argon, krypton, xenon, radon, and oganesson of Group 18 of the periodic table are Noble or Inert gases.

Radon is the heaviest and Helium is the lightest gases of the noble gases.

Rounding off a value means replacing it by a nearest value that is approximately equal or smaller or greater to the given number.

y = (int)(x + 0.5); here x is any float value. To roundoff, we have to typecast the value of x by using (int)

Example:

#include

int main ()

{

  float x = 2.6;

  int y = (int)(x + 0.5);

  printf ("Result = %d\n", y );

  return 0;

}

Result : 3

Orographic precipitation or Rain produced when moist air is lifted as it moves over a mountain range. As the air rises and cools, orographic clouds form and serve as the source of the precipitation, most of which falls upwind of the mountain ridge.

Some also falls a short distance downwind of the ridge and is sometimes called spillover. On the lee side of the mountain range, rainfall is usually low, and the area is said to be in a Rain Shadow. 

Envelope is a letter holder for one letter and in the question it mean that it holds one letter. Eye is also a word which starts and end with E but has one letter in the middle.

Sulphur is an yellow element that stinks when burned.