Sodium Vapor Lamp is usually used as street light, because –
Correct Answer:
(B)
Light from this is monochromatic and will not split through water droplets.
A sodium-vapor lamp is a gas-discharge lamp that uses sodium in an excited state to produce light. Low-pressure sodium lamps only give monochromatic yellow light and so inhibit colour vision at night and will not split through water droplets. Sodium-vapor lamps cause less light pollution than mercury-vapor lamps.
Ques:
42
Which one of the following metals is accessed in the native state ?
Correct Answer:
(B)
Gold
Among the given metals, gold is the least reactive, so this was accessed in the native (free) state. Only gold, silver, copper and platinum metals occur in native state in nature in large amounts.
Ques:
43
Of how many carats is the pure gold?
Correct Answer:
(B)
24
It is an extension of the older carat (Karat in American spelling) system of denoting the purity of gold by fractions of 24, such as '18 carat' for an alloy with 75% (18 parts per 24) pure gold by mass. Because of the softness of pure (24 carat) gold, it is usually alloyed with base metals for use in jewellery, altering its hardness and ductility, melting point, colour and other properties. Alloys with lower carat rating typically 22k, 18k, 14k or 10k contain higher percentages of copper or other base metals or silver or palladium in the alloy.
Ques:
44
Minerals are-
Correct Answer:
(B)
Inorganic solids
According to Geologists, minerals are naturally occurring inorganic substances with a definite and predictable chemical composition and physical properties.
Ques:
45
The softest mineral, Talc (Soapstone) is mainly :
Correct Answer:
(D)
Magnesium Silicate
Talc is a mineral which is composed of hydrated Magnesium silicate with formula Mg3 Si4O10(OH)2. On the Mohs hardness scale, the softest mineral talc is rated 1 and the hardest mineral, the diamond is rated 10. In loose form, talc is the widely used substance known as a baby powder (aka talcum). It occurs as foliated to fibrous masses and in an exceptionally rare crystal form.
Ques:
46
The chemical name of limestone is?
Correct Answer:
(A)
Calcium Carbonate
Limestone is a sedimentary rock composed largely of the minerals Calcite and Aragonite which are different crystal forms of Calcium Carbonate (CaCO3). Limestone binds with silica and other impurities to remove them from the iron.
Ques:
47
'Plaster of Paris' is made up of
Correct Answer:
(C)
Gypsum
Plaster of Paris is a white powdery slightly hydrated calcium sulfate (CaSO4.1/2 H2O) made by calcining gypsum and used mainly for casts and molds in the form of a quick-setting paste with water.
Ques:
48
Which one of the following materials contains calcium?
Correct Answer:
(C)
Gypsum
Gypsum is a soft sulfate mineral which contains calcium. It is composed of calcium sulphate dihydrate, with the chemical formula CaSO4.2H2O. It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard/sidewalk chalk, and drywall.
Ques:
49
Monazite is an ore of –
Correct Answer:
(B)
Thorium
Monazite is an important ore for Thorium, Lanthanum and Cerium. India, Madagascar and South Africa have large deposits of monazite sands. The deposits in India are particularly rich in Monazite. Its extensive deposits are found in Southern India.
Ques:
50
Mica is a :
Correct Answer:
(A)
Good conductor of heat and bad conductor of electricity
(1) Good conductors of electricity are : Aluminum, Brass, Copper, Iron, Steel
(2) Bad conductors of electricity are : Acrylic, China clay, Glass, Mica, Paper, Plastic & Wood. Mica is a bad conductor of electricity but a good conductor of heat. It is used as a raw material in electrical industry.