General Science Questions

An elastomer is a polymer with viscoelasticity which have low youngs modulus with weak intermolecular forces when compared with other materials.

A daisy-wheel printer works on the same principle as a ball-head typewriter. Daisy wheel printer is a type of impact printer invented in 1969.

The daisy wheel is a disk made of plastic or metal on which characters stand out in relief along the outer edge. To print a character, the printer rotates the disk until the desired letter is facing the paper.

When you can't hear it is called as Deaf.

Secondary succession means in an ecosystem renewal of itself after all or a portion has been destroyed.

After a forest fire, the whole forest had destroyed but after that again renewal of that forest is also an example of secondary succession.

The plants which flower only once in their lifetime are called Monocarpic Plants.

Matching blood group before marriage is important. This is to prevent Rh incompatibility. Rh incompatibility can lead to erythroblastosis fetalis (Hemolytic disease of the newborn-HDN). Fetal RBC gets destroyed & newborn may get severe anaemia, jaundice. This jaundice is more severe than Physiological jaundice ( which is the most common and will usually resolve on its own).

In very severe form, a fetus may die due to heart failure. This is mediated by the antigen-antibodies reaction. Transfer of maternal antibodies across the placenta occurs. This happens when Rh +ve man marries Rh-ve lady.

So Rh +ve man should try to avoid marrying Rh-ve lady.

Matching blood groups for marriage ::

Boy : A = Girl : A & AB 

Boy : B = Girl : B & AB 

Boy : O = Girl : O, A, B & AB 

Boy : AB = Girl : AB 

Boy : Rh+ve = Girl : Rh+ve 

Boy : Rh-ve = Girl : Rh+ve & Rh-ve.

Blood groups that do not match for marriage ::

Boy : A = Girl : O & B 

Boy : B = Girl : O & A 

Boy : AB = Girl : O, A & B 

Boy : Rh+ve = Girl : Rh-ve.