511: Which one of the following is paramagnetic in nature ?
(a) Iron
(b) Hydrogen
(c) Oxygen
(d) Nitrogen
Explanation:
Oxygen at standard Temperature and Pressure is paramagnetic in nature. Other examples are Al, Na, Ca and CuCl2. The individual atoms or ions or molecules of a paramagnetic material possess permanent dipole moment of their own. While a diamagnetic material do not possess a permanent dipole moment of their own.
512: Consider the following kinds of organisms :
1. Bat
2. Bee
3. Bird
Which of the above is/are pollinating agent/agents?
(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3
Explanation:
The primary agents of pollination, other than air, are bees and other insects, birds, and bats. The humming bird is the best-known bird pollinator, but there are other nectar-eating birds which act as pollinators, for example the less well known honey creeper of Hawaii, sunbirds, sugarbirds, and brushtongued parrots. Like other pollinating agents, bees pollinate as part of their own food gathering. Most bat species that pollinate flowers inhabit Africa, Southeast Asia, and the Pacific Islands, although bat pollination occurs over a geographically wide range. Many fruits are dependent on bats for pollination, such as mongoes, bananas, and guavas (USDA 2006). Zoophily is a form of pollination whereby pollen is transferred by vertebrates, particularly by hummingbirds and other birds, and bats, but also by monkeys, marsupials, lemurs, bears, rabbits, deer, rodents, lizards and other animals.
The term ornithophily is used to describe pollination specifically by birds. Hummingbirds, found only in North and South America, are the most recognized nectar-eating bird, but there are many other bird species throughout the world that also are important pollinators. These include: sunbirds, honeyeaters, flowerpeckers, honeycreepers, and bananaquits (EEB 2006).
Plants pollinated by birds often have brightly colored diurnal flowers that are red, yellow, or orange, but no odor because birds have a poor sense of smell. Other charcteristics of these plants are that they typically have suitable, sturdy places for perching (though hummingbirds can hover) and abundant nectar that is deeply nested within the flower. Often flowers are eleogated or tube shaped. Also, many plants have anthers placed in the flower so that pollen rubs against the birds head/back as the bird reaches in for nectar (USDA 2006).
513: Which one of the following has the highest fuel value ?
(a) Hydrogen
(b) Charcoal
(c) Natural Gas
(d) Gasoline
Explanation:
The fuel value or calorific value is defined as the amount of heat produced in calories or joules when one gram of a substance (fuel) is completely burnt.
514: Which one of the following is monogamous?
(a) Wolf
(b) Walrus
(c) Seal
(d) Deer
Explanation:
Wolf is monogamous which maintains single mate for sexual intercourse.
Polygamous : Having more than one mate at a time like Deer, Cattle, Walrus, Seal etc.
515: Which one of the following is used as an anti-freeze for the automobile engines?
(a) Propyl alcohol
(b) Ethanol
(c) Methanol
(d) Ethylene glycol
Explanation:
Ethylene glycol is used as an anti-freeze for the automobile engines to help prevent the freezing of fuel under sub zero conditions in temperate regions.