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.

Given that, a woman has seven children. Half of them are boys. 

Half of 7 is 3.5 which is not possible. And it is possible in only one way that all the children must be boys. Then half of them are boys.

She was born on November 29, 1899. She was from Italy. She held the Guinness World Record titles for oldest living person and oldest living woman.

The Teesta River is a 309 km long river flowing through the Indian states of West Bengal and Sikkim, before going to Bay of Bengal through Bangladesh.

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.