Chemistry - Study Mode
[#571] The chemical name of 'Hypo' commonly used in photography is
Correct Answer
(A) Sodium thiosulphate
Explanation
Solution: An emulsion of sodium thiosulfate is called hypo by photographers. It is used to stop development of exposed film. Thiosulfate converts undeveloped silver bromide grains in the film into water-soluble silver thiosulfate complexes that can be removed when the film is washed.
[#572] Interveinal necrotic spots on leaves appear due to
Correct Answer
(B) SO 2 injury
Explanation
Solution: Injury caused by sulphur oxides show interveinal necrotic areas that are light tan to white. Uninjured tissue next to the veins remains green.
[#573] Quartz is made of
Correct Answer
(D) Sodium Silicate
Explanation
Solution: Quartz is an abundant mineral in the Earth’s continental crust. It is made up of a continuous framework of SiO 4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO 2 . There are many different varieties of quartz, several of which are semiprecious gemstones. Most quartz used in microelectronics is produced synthetically. Large, flawless and un-twinned crystals are produced in an autoclave via the hydrothermal process. The process involves treating crushed natural quartz with hot aqueous solution of a base such as sodium hydroxide.
[#574] Cement is formed by strongly heating a mixture of
Correct Answer
(B) Limestone and clay
Explanation
Solution: Cement is made by heating limestone (calcium carbonate) with small quantities of other materials (such as clay) to 1450 degree C in a kiln, in a process known as calcination, whereby a molecule of carbon dioxide is liberated from the calcium carbonate to form calcium oxide, or quicklime, which is then blended with the other materials that have been included in the mix. The resulting hard substance, called ‘clinker’, is then ground with a small amount of gypsum into a powder to make ‘Ordinary Portland Cement’, the most commonly used type of cement (often referred to as OPC). Portland cement is a basic ingredient of concrete, mortar and most non-specialty grout. The most common use for Portland cement is in the production of concrete.
[#575] Persons working in cement plants and lime stone quarries are prone to disease like
Correct Answer
(C) Silicosis
Explanation
Solution: Silicosis is caused due to lung fibrosis caused by the inhalation of dust containing silica. Since the person is working in cement plants and limestone quarries and cement is made up of silica, lime, alumina etc. so, the person is most affected or prone to the disease known as Silicosis.