Questions

In transfusions of packed red blood cells, individuals with type O Rh D negative blood are often called universal donors. Those with type AB Rh D positive blood are called universal recipients.

The immune system of a person with AB blood will accept blood from all possible donors, whether they have O, A, B, or AB blood. Since both A and B antigens are present in a person with AB blood, the recipient won't reject the blood. The body identifies that blood as "self" rather than "foreign."

Atoms are composed of three main particles called electrons, protons and neutrons. We know that, the electrons are negatively charged particles whereas protons are positively charged and neutrons have no charge.

Hence, as the number of electrons and protons are equal and they are oppositely charged, the atom will have no charge as their charges cancel each other.

The great Sahara Desert created an opportunity for wealth by trading to peoples who live in and around the region. The city of Timbuktu was built as a result of this trade.

Hundreds of years ago, salt was a very valuable commodity. It was valued for its taste as well as its ability to preserve food. One of the most productive areas for producing salt was the Sahara Desert, and the city of Timbuktu was built to capitalize upon this trade.

A Keyboard has keys but no locks.

From the cornea, the light passes through the pupil. From there, it then hits the lens, the transparent structure inside the eye that focuses light rays onto the retina. The iris, or the colored part of your eye, regulates the amount of light passing through. 

The freedom of expression is in amendment-1 of the Indian constitution.