General Science Questions (MCQs) for Competitive Examinations

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Steel is an alloy made by combining iron and other elements, the most common of these being carbon. When carbon is used, its content in the steel is between 0.2% and 2. 1% by weight, depending on the grade. Other alloying elements sometimes used are manganese, chromium, vanadium and tungsten. Carbon and other elements act as a hardening agent, preventing dislocations in the iron atom crystal lattice from sliding past one another.

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Radon, a radioactive noble gas with atomic number 86, is used in radiotherapy. Created by disintegration of radium, its one of the heaviest gases and a health hazard. Radon gas, chemically inert yet radioactive, can accumulate in buildings and drinking water causing lung cancer. Furthermore, radon is noted for brilliant phosphorescence when cooled below its freezing point. Its most stable isotope, 222Rn, has a half-life of 3.8 days. Groundwater often has a higher 222Rn concentration than surface water due to less exposure to atmosphere.

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Turner syndrome is a rare chromosomal disorder characterized by partial or complete loss (monosomy) of one of the X chromosomes that affects females. Individuals with Turner syndrome have only 45 chromosomes, including just a single X chromosome. This monosomic has a chromosome complement of 44 autosomes and one X chromosome (44+XO). The abnormal condition probably originates from exceptional egg or sperm with no X chromosome.

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According to 11th Fiver Year Plan, the Second Green Revolution aims to meet the problems of small and marginal farmers for providing income security to a large section of rural households and treating them as partners of development instead of a mere beneficiary of some government schemes or programme.

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The ear has three main parts: the outer, middle and inner ear. The outer ear consists of the pinna and the auditory canal. The middle ear is filled with air and contains three tiny bones called ossicles – the anvil, hammer and stirrup. The inner ear contains the semicircular canals and the cochlea. Eardrum is the membrane of middle ear. Snakes have fully developed inner ear structures but no eardrum.

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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.

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The small intestine, the part of the gastrointestinal tract between the stomach and the large intestine, is the main digester and absorber of food. The small intestine has three distinct regions – the duodenum, jejunum, and ileum–that carry out the absorption of nutrients and minerals from food. It converts the food into a semi-solid mass.

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It is assumed that protodermal cells divide periclinally in certain cases to form multiseriate or multiple epidermis. The multiple epidermis is found in some organs like roots of orchids (Vanda), leaves of Ficus, Nerium, Piperomia, etc. In Nerium, it is found on both surfaces.

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Skeletal muscle is a form of striated muscle which is under the voluntary control of the somatic nervous system. Most skeletal muscles are attached to bones by bundles of collagen fibres known as tendons. It is one of three major muscle types, the others being cardiac muscle and smooth muscle.

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Solitary cymose inflorescence refers to a determinate inflorescence composed of a single flower. Examples include poppy, gardenia (ornamental plant), tulip, etc. Flowers are said to be solitary when the plant bears only one, or when single flowers appear on the ends of lateral branches that are remote from one another.