General Science Questions (MCQs) for Competitive Examinations

Notes:
Magnetite (Fe3O4) typically contains about 70% iron by weight. It is black in color and strongly magnetic. Hematite (Fe2O3) contains about 60–70% iron. Limonite contains 35–50% iron. Siderite (FeCO3) contains about 48% iron. Magnetite is widely mined due to its high iron concentration compared to other ores.

Notes:
Chemical weapons are called “poorman’s bomb”. These cause catastrophic damage, and are easy to produce. Sarin is a colorless and odourless agent, and is extremely potent. It was used in Damascus in 2013. Mustard Gas is possibly the most commonly used chemical agent and gets its name from the distinctive odour of rotten mustard. It is less potent and usually only 5 to 10 percent people exposed to it usually die. It was widely used during Second World War. VX is a nerve agent which is odourless and appears as brownish oily substance.

Notes:
Heavy water is water that contains heavy hydrogen or deuterium. Deuterium differs from the hydrogen usually found in water, protium, in that each atom of deuterium contains a proton and a neutron. Heavy water may be deuterium oxide, D2O or it may be deuterium protium oxide, DHO.

Notes:
The right pulmonary artery is longer and larger and runs horizontally outward in front of right main bronchus and behind the superior vena cava, to the base of the right lung where it divides in two branches. The left pulmonary artery is shorter and runs horizontally over the left upper division bronchus, to the base of the left hilum where it divides into two branches.

Notes:
The wings of insects, bats and birds, that evolved independently in each lineage separately after diverging from an ancestor without wings, are examples of analogous organs. Analogous organs are the opposite of homologous organs, which have similar functions but different origins.

Notes:
The pore is bordered by a pair of specialized parenchyma cells known as guard cells that are responsible for regulating the size of the opening. Guard cells are specialized cells in the epidermis of leaves, stems and other organs that are used to control gaseous exchange and rate of transpiration.

Notes:
Infection is the invasion of an organism’s body tissues by disease-causing agents, their multiplication, and the reaction of host tissues to the infectious agents and the toxins they produce. Infectious diseases can be spread from one person to another, for example through contact with bodily fluids, by aerosols (through coughing and sneezing), or via a vector, for example a mosquito.

Notes:
Barani area are traditionally rain-fed areas. These are any low rain area where the rain-fed dry farming is practiced. Bagar tract, the dry sandy tract of land on the border of Rajasthan state adjoining the states of Haryana and Punjab, is an example of Barani land.

Notes:
Both polio and chicken pox are caused by virus. Poliomyelitis, often called polio or infantile paralysis, is an infectious disease caused by the poliovirus; while, Chickenpox, also known as varicella, is a highly contagious disease caused by the initial infection with varicella zoster virus (VZV).

Notes:
An accessory fruit (sometimes called false fruit, spurious fruit, pseudo-fruit, or pseudo-carp) is a fruit in which some of the flesh is derived not from the ovary but from some adjacent tissue exterior to the carpel. Examples of accessory tissue are the receptacle of strawberries, figs, or mulberries, and the calyx of Gaultheria procumbens or Syzygium jambos. Pomes, such as apples and pears, are also accessory fruits, with much of the fruit flesh derived from a hypanthium.