QUES: In nature, the red color of blood comes from hemoglobin, the iron-containing protein found in the red blood cells of all vertebrates. The red color of the Grand Canyon and other geological features is caused by hematite or red ochre, both forms of iron oxide. It also causes the red color of the planet Mars. The red sky at sunset and sunrise is caused by an optical effect known as Rayleigh scattering, which, when the sun is low or below the horizon, increases the red-wavelength light that reaches the eye. The color of autumn leaves is caused by pigments called anthocyanins, which are produced towards the end of summer, when the green chlorophyll is no longer produced. One to two percent of the human population has red hair; the color is produced by high levels of the reddish pigment pheomelanin (which also accounts for the red color of the lips) and relatively low levels of the dark pigment eumelanin.

What causes the color of hematite and red ochre?
What is the answer?
ANS: iron oxide
QUES: The theory of special relativity finds a convenient formulation in Minkowski spacetime, a mathematical structure that combines three dimensions of space with a single dimension of time. In this formalism, distances in space can be measured by how long light takes to travel that distance, e.g., a light-year is a measure of distance, and a meter is now defined in terms of how far light travels in a certain amount of time. Two events in Minkowski spacetime are separated by an invariant interval, which can be either space-like, light-like, or time-like. Events that have a time-like separation cannot be simultaneous in any frame of reference, there must be a temporal component (and possibly a spatial one) to their separation. Events that have a space-like separation will be simultaneous in some frame of reference, and there is no frame of reference in which they do not have a spatial separation. Different observers may calculate different distances and different time intervals between two events, but the invariant interval between the events is independent of the observer (and his velocity).

What are two events in Minkowski spacetime connected by?
What is the answer?
ANS: unanswerable
QUES: In the year 712, Muhammad bin Qasim, an Umayyad general, sailed from the Persian Gulf into Sindh in Pakistan and conquered both the Sindh and the Punjab regions along the Indus river. The conquest of Sindh and Punjab, in modern-day Pakistan, although costly, were major gains for the Umayyad Caliphate. However, further gains were halted by Hindu kingdoms in India in the battle of Rajasthan. The Arabs tried to invade India but they were defeated by the north Indian king Nagabhata of the Pratihara Dynasty and by the south Indian Emperor Vikramaditya II of the Chalukya dynasty in the early 8th century. After this the Arab chroniclers admit that the Caliph Mahdi "gave up the project of conquering any part of India."

At what battle did the Hindus of India defeat the Umayyads?
What is the answer?
ANS:
Rajasthan