QUES: The European colonization of the Americas forever changed the lives and cultures of the peoples of the continents. Although the exact pre-contact population of the Americas is unknown, scholars estimate that Native American populations diminished by between 80 and 90% within the first centuries of contact with Europeans. The leading cause was disease. The continent was ravaged by epidemics of diseases such as smallpox, measles, and cholera, which were brought from Europe by the early explorers and spread quickly into new areas even before later explorers and colonists reached them. Native Americans suffered high mortality rates due to their lack of prior exposure to these diseases. The loss of lives was exacerbated by conflict between colonists and indigenous people. Colonists also frequently perpetrated massacres on the indigenous groups and enslaved them. According to the U.S. Bureau of the Census (1894), the North American Indian Wars of the 19th century cost the lives of about 19,000 whites and 30,000 Native Americans.
How much did the population of the Americas decrease after first contact with the Europeans?

ANS: between 80 and 90%

QUES: At the end of the Second World War, Canada possessed the fourth-largest air force and fifth-largest naval surface fleet in the world, as well as the largest volunteer army ever fielded. Conscription for overseas service was introduced only near the end of the war, and only 2,400 conscripts actually made it into battle. Originally, Canada was thought to have had the third-largest navy in the world, but with the fall of the Soviet Union, new data based on Japanese and Soviet sources found that to be incorrect.
How many conscripts made it into the naval surface fleet?

ANS: unanswerable

QUES: Ducks are medium-sized aquatic birds with broad bills, eyes on the side of the head, fairly long necks, short legs set far back on the body, and webbed feet. Males, known as drakes, are often larger than females (simply known as ducks) and are differently coloured in some breeds. Domestic ducks are omnivores, eating a variety of animal and plant materials such as aquatic insects, molluscs, worms, small amphibians, waterweeds, and grasses. They feed in shallow water by dabbling, with their heads underwater and their tails upended. Most domestic ducks are too heavy to fly, and they are social birds, preferring to live and move around together in groups. They keep their plumage waterproof by preening, a process that spreads the secretions of the preen gland over their feathers.
How can you identify a duck from other poultry?

ANS: medium-sized aquatic birds with broad bills, eyes on the side of the head, fairly long necks, short legs set far back on the body, and webbed feet.

QUES: Throughout the universe, hydrogen is mostly found in the atomic and plasma states whose properties are quite different from molecular hydrogen. As a plasma, hydrogen's electron and proton are not bound together, resulting in very high electrical conductivity and high emissivity (producing the light from the Sun and other stars). The charged particles are highly influenced by magnetic and electric fields. For example, in the solar wind they interact with the Earth's magnetosphere giving rise to Birkeland currents and the aurora. Hydrogen is found in the neutral atomic state in the interstellar medium. The large amount of neutral hydrogen found in the damped Lyman-alpha systems is thought to dominate the cosmological baryonic density of the Universe up to redshift z=4.
The neutral hydrogen found in the damped Lyman-alpha systems dominates what?

ANS:
cosmological baryonic density of the Universe