Questions

The red blood corpuscles or Erythrocytes usually carry antigens and there are two types of antigens. The A group persons have antigen A in their red corpuscles and the B group have antigen A in their red corpuscles.The AB group persons have both antigen A and antigen B in their erythrocytes.The 'O'group persons have no antigens in their red corpuscles.

mercaptans (or thioalcohols) have a foul odour

In this chemical reaction chlorine change oxidation number from 0 to -1 (reduction) and bromine change oxidation number from -1 to 0 (oxidation).

Chlorine is stronger oxidation reagent than bromine.

In VIIA or group 17 (halogen elements) there are six elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At) and tennessin(Ts).

They have high electronegativity because they have seven valence electrons in their outermost energy level, so they can gain an electron to have the octet rule.  

Going down in the group, element are weaker oxidazing reagent and less reactive.

The Highest bridge in the world is Bailey bridge. It is located in the Ladakh valley between Dras and Suru rivers in the Himalayan mountains. It was built by the Indian Army in August 1982.

It is 30 meters (98 ft) long and is at an altitude of 5,602 meters (18,379 ft) above sea level.