Description : Setting of plaster of paris involves – (1) dehydration process (2) hydration to form other hydrates (3) oxidation process (4) reduction process
Last Answer : (2) hydration to form other hydrates Explanation: The setting of plaster of Paris takes place by hydration due to the formation of a solid crystalline hydrate and hardening of Plaster of Paris is ... . A slight expansion takes place in the process and heat is evolved. This process is exothermic.
Description : Setting of plaster of paris involves (1) dehydration process (2) hydration to form other hydrates (3) oxidation process (4) reduction process
Last Answer : hydration to form other hydrates
Description : Pick up the incorrect statement from the following: (A) The degree of grinding of cement, is called fineness (B) The process of changing cement paste into hard mass, is known as setting of ... (D) The heat generated during chemical reaction of cement with water, is known as heat of hydration
Last Answer : Answer: Option C
Description : Tricalcium aluminate (C3A) (A) Reacts fast with water (B) Generates less heat of hydration (C) Causes initial setting and early strength of cement (D) Does not contribute to develop ultimate strength
Last Answer : Answer: Option B
Description : The setting and hardening of cement after addition of water is due to a) Binding action of water b) Evaporation of water c) Hydration and hydrolysis of some constituent compounds of cement* d) Additional hardening compounds added to cement
Last Answer : c) Hydration and hydrolysis of some constituent compounds of cement*
Description : Setting of cement is due to the hydration of calcium silicates and?
Last Answer : Calcium aluminates
Description : The deleterious materials present in the aggregate (a) Prevent normal hydration of cement (b) Reduce the strength and durability of concrete. (c) Modify the setting action and cause efloresecence. (d) All of the above
Last Answer : (d) All of the above
Description : Rusting is the process of – (1) Oxidation (2) Reduction (3) Decomposition (4) Displacement
Last Answer : (1) Oxidation Explanation: Rust is the process of iron (molecules) oxidizing into iron oxide, or rust. General formula of rust is Fe2O3.nH2O
Description : Addition of pozzolana to cement causes (A) Reduction in permeability (B) Loss of heat of hydration (C) Reduction in bleeding (D) All the above
Last Answer : Answer: Option D
Description : Which of the following reactions involve NEITHER oxidation nor reduction? w) burning antimony in chlorine x) decomposition of potassium chlorate y) reaction of sodium with water z) reaction of potassium hydroxide with nitric acid
Last Answer : ANSWER: Z -- REACTION OF POTASSIUM HYDROXIDE WITH NITRIC ACID
Description : Decomposition of the acetyl salicylic acid at room temperature most likely would occur by (a) Oxidation of the ester (b) Reduction of the carboxylic acid (c) Hydrolysis of the ester
Last Answer : Ans: C
Description : The working of a dry cell is based on - (1) Decomposition reaction (2) Spontaneous oxidation-reduction reaction (3) Combination reaction. (4) Electrolysis
Last Answer : (4) Electrolysis Explanation: A dry cell is a type of battery that uses a paste electrolyte, with only enough moisture to allow current to flow. It works in accordance with Faraday's law of ... of the cell (the positive electrode), and the space between them is filled with an electrolyte paste.
Description : Bleaching action of chlorine is by - (1) Decomposition (2) hydrolysis (3) reduction (4) oxidation
Last Answer : (4) oxidation Explanation: Chlorine bleaches by the process of oxidation. It needs moisture for its bleaching action. Chlorine reacts with water to form hydrochloric and hypochlorous acids.
Description : Sulphur dioxide bleaches colouring matter by – (1) Reduction (2) Dehydration (3) Decomposition (4) Oxidation
Last Answer : (1) Reduction Explanation: Sulphur dioxide gas exhibits bleaching properties in presence of moisture. It dissolves in water liberating nascent hydrogen. Nascent hydrogen removes oxygen atoms from the colouring matter (reduces colouring matter) and it loses its colour.
Description : CuO + H2 = Cu + H2O. This equation is an example of - (1) Oxidation (2) Decomposition (3) Reduction (4) Redox
Last Answer : (4) Redox
Description : Bleaching action of chlorine is by - (1) decomposition (2) hydrolysis (3) reduction (4) oxidation
Description : Which of the following is a physical change? (1) oxidation (2) reduction (3) sublimation (4) decomposition
Last Answer : (3) sublimation Explanation: Sublimation is a type of phase transition, or a change in a state of matter, just like melting, freezing, and evaporation.
Description : Bleaching action of chlorine is by----? A. Oxidation (Answer) B. Reduction C. Decomposition D. Hydrolysis
Last Answer : A. Oxidation (Answer)
Description : Rusting of Iron involves--------? A. Reduction B. Oxidation (Answer) C. Decomposition D. Displacement
Last Answer : B. Oxidation (Answer)
Description : During decomposition, energy is absorbed in the form of heat, light or electricity for breaking down the reactants which is known as: (a) exothermic reaction (b) endothermic reaction (c) reduction reaction (d) oxidation
Last Answer : (b) endothermic reaction
Description : Which two distinct microbial processes are responsible for the release of fixed nitrogen as dinitrogen gas (N2) to the atmosphere? (a) Aerobic nitrate oxidation and nitrite reduction (b) ... fixation by Rhizobium in root nodules of legumes (d) Anaerobic ammonium oxidation and denitrification
Last Answer : (d) Anaerobic ammonium oxidation and denitrification
Description : The working of a dry cell is based on (1) Decomposition reaction (2) Spontaneous oxidation-reduction reaction (3) Combination reaction (4) Electrolysis
Last Answer : Electrolysis
Description : Sulphur dioxide bleaches colouring matter by : (1) Reduction (2) Dehydration (3) Decomposition (4) Oxidation
Last Answer : Reduction
Description : The process of conversion of plastic concrete to solid stage is called [ A ] Hydration [ B ] Hardening [ C ] Setting [ D ] Curing
Last Answer : [ C ] Setting
Description : Differentiate between retarding and accelerating admixtures with following points. i) Hydration process ii) Setting time iii) Weather condition iv) Use
Last Answer : The accelerating and retarding admixtures can be compared as follows. Accelerating Admixture Retarding Admixture Hydration process Due to accelerating admixture, hydration process completes ... where slow hardening of concrete is necessary i.e. in mass concrete structures.
Description : During the process of hardening of cement, _______ will takes place [ A ] Bleeding [ B ] Segregation [ C ] Hydration [ D ] All the above
Last Answer : [ C ] Hydration
Description : The addition of gypsum to portland cement helps in : (1) increasing the strength of cement (2) rapid setting of cement (3) preventing rapid setting of cement (4) reduction in the cost of cement
Last Answer : preventing rapid setting of cement
Description : Setting of plaster of Paris is accompanied with (A) Hydration (B) Dehydration (C) Hydrolysis (D) Loss of CO2
Last Answer : (A) Hydration
Description : The reduction of the PH value, by the action of atmospheric carbon dioxide with the alkali of the cement paste is called [ A ] atmospheric corrosion [ B ] chloride corrosion [ C ] oxidation [ D ] carbonation
Last Answer : [ D ] carbonation
Description : A tube mill as compared to a ball mill (A) Employs smaller balls (B) Gives finer size reduction but consumes more power (C) Has larger length/diameter ratio (>2 as compared to 1 for ball mill) (D) All (A), (B) and (C)
Last Answer : (D) All (A), (B) and (C)
Description : Which of the following size reduction equipments employs mainly attrition for ultrafine grinding? (A) Jet mills (B) Fluid energy mill (C) Micronizer (D) All (A), (B) and (C)
Description : Atmospheric corrosion of metals result from their (A) Slow oxidation (B) Fast oxidation (C) Fast hydration (D) Slow dehydration
Last Answer : (A) Slow oxidation
Description : Hydration of cement is due to chemical action of water with (A) Tricalcium silicate and dicalcium silicate (B) Dicalcium silicate and tricalcium aluminate (C) Tricalcium aluminate and tricalcium alumino ferrite (D) All the above
Description : The condition not applicable to water cement ratio law, is (A) Internal moisture conditions on hydration continue till complete strength is gained (B) Concrete specimens may be tested at any temperature (C) Concrete specimens need be of same age (D) Concrete specimens need be of same size
Description : Pick up the correct statement from the following: (A) Water cement paste hardens due to hydration (B) During hardening cement binds the aggregates together (C) Cement provides strength, durability and water tightness to the concrete (D) All the above
Description : Concrete gains strength due to (A) Chemical reaction of cement with sand and coarse aggregates (B) Evaporation of water from concrete (C) Hydration of cement (D) All the above
Description : Hydration of cement is due to the chemical action of water with. (a) Tricalcium silicate (b) Dicalcium silicate (c) Tricalcium aluminate (d) All of these
Last Answer : (d) All of these
Description : Concrete gains strength due to [ A ] Chemical reaction of cement with sand and coarse aggregates [ B ] Evaporation of water from concrete [ C ] Hydration of cement [ D ] All the above
Last Answer : [ C ] Hydration of cement
Description : Cement is made hard with (1) dehydration (2) hydration and dissociation of water (3) Dissociation of water (4) Polymerisation
Last Answer : hydration and dissociation of water
Description : Write the significance of water-cement ratio and its effect on hydration of cement.
Last Answer : Significance of water-cement ratio: The W/C ratio plays very vital role in concrete mixture. The improper or random selection of W/C ratio leads in various defects in fresh and hardened concrete ... of water for sufficient hydration. But such large water may not give proper binding of aggregates.
Description : When water itself combines chemically with some element or mineral it is called – (1) Carbonation (2) Desilication (3) Hydration (4) Oxidation
Last Answer : (3) Hydration Explanation: When water combines chemically with other elements, the process is called hydration. In organic chemistry, a hydration reaction is a chemical reaction in which a hydroxyl ... runs in a strong acidic, aqueous solution. Hydration leaves the non-water component intact.
Description : When water itself combines chemically with some element or mineral it is called (1) Carbonation (2) Desilication (3) Hydration (4) Oxidation
Last Answer : Hydration
Description : What is the first stage of hydration in cement?
Last Answer : Need answer
Description : When each particle of aggregates is thinly coated with cement paste, a heterogeneous solid is formed, which is known as (A) Hydration (B) Gel (C) Concrete (D) None of these
Description : Addition of pozzolana to cement (A) Decreases workability (B) Increases strength (C) Increases heat of hydration (D) None of these
Description : Pick up the correct statement from the following: (A) The concrete gains strength due to hydration of cement (B) The concrete does not set at freezing point (C) The strength of concrete increases with its age (D) All the above
Description : Di-calcium silicate (C2S) (A) Hydrates rapidly (B) Generates less heat of hydration (C) Hardens rapidly (D) Provides less ultimate strength to cement
Description : Portland pozzolana cement possesses (A) Higher resistance to chemical attack (B) Lower heat of hydration (C) Lower shrinkage on drying (D) All the above
Description : Addition of pozzolana to ordinary Portland cement increases (A) Bleeding (B) Shrinkage (C) Permeability (D) Heat of hydration