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Right choice is (B) 0.3-0.6%

For EXPLANATION: The sequence of composition is in order from low carbon steel to high carbon steel TILL 1.7% carbon. Medium carbon steel belongs to a REGION of 0.3-0.6% carbon.

The correct CHOICE is (b) Hot strength THEORY

Easiest explanation: Hot strength theory is not one of the bonding THEORIES, while ELECTROSTATIC theory, surface tension theory and block and WEDGE theory are bonding theories.

Right answer is (a) True

Explanation: The Large particles in SOIL increase the chances of imperfections and BRITTLE failure. REVERSELY, smaller particles are strengthened by the decrease in imperfections. This MAKES the failure advantageous that occurs due to the presence of cleavage at the crystal planes. High cooperating conditions increases the breaking of extended particles and shear abrasion.

Right choice is (a) 1725°C

Explanation: Quartz gets MELTED completely at 1725°C. After REACHING this TEMPERATURE, the quartz WOULD then start undergoing transformations.

Right answer is (C) 1/7 kg/cm^2

Explanation: The GREEN compression strength of core sand mixture for general purpose is 1/7 kg/cm^2, whereas the DRY compression strength of a core sand mixture is FOUND to be 70 kg/cm^2.

Right CHOICE is (b) WAX

To explain I would say: For the core material, water, granular refractories and core BINDERS are ingredients which are HIGHLY used. The ingredients used do not INVOLVE wax in it and hence is not a part of the ingredients.

Correct choice is (d) Dextrin and molasses

The EXPLANATION is: Dextrin and molasses are used for increasing the dry STRENGTH of the SAND, which add HARDNESS to the MOULD.

Right option is (a) 10%

Explanation: Sea COAL otherwise is used in SMALL numbers for binding. Sea coal is used for surface APPEARANCE IMPROVEMENT. It is used about 10% in cast iron moulding sands for large green casting sands.

The correct OPTION is (d) Permeability

Explanation: CONDUCTIVITY, thermal EXPANSION and size of the particle are few of the factors needed to be CONSIDERED while selecting a refractory and not permeability.

Right answer is (a) 5%

Easiest explanation: In green SAND, the amount of clay that is NEEDED in PERCENTAGE composition is around 15% to 30%. The amount of water in terms of percentage composition is about 5%.

The correct option is (b) False

To elaborate: Ball clay normally has water content nearly about 28 percent. To decrease moisture content, they are stored in drying SHEDS. Then the clay is SHREDDED into SMALL pieces which are further dried by the use of hammer mill. Extracted scrap material from the hammer mill is BLENDED with water to form a slurry mixture for further use.

Correct ANSWER is (a) 2-3%

The explanation is: In gray cast irons of facing sand mixtures, the bentonite percentage composition is CALCULATED to be 2-3%. Whereas, in the case of GREEN SANDS, the bentonite percentage is recorded to be around 3.5%.

Right CHOICE is (a) True

The explanation is: For the analysis of small size GRAINS of soils in hydrometer test, soil sample used should be DISPERSED first in order to eliminate the particle coagulation. This is mainly accomplished by blending of soil with the solution of sodium hexametaphophate and then stirring is done to get a PROPER UNIFORM solution.

Right option is (B) False

The best I can explain: Analysis of very small size GRAINS of soil cannot be possible by using SIEVES, because of very small size of SIEVE openings, it is very difficult to get PASS the grains. Then for the analysis of small size grains, hydrometer analysis is done which is based on stoke’s law that states that the larger the grain size, the larger it’s settling speed in a fluid.

The correct OPTION is (c) Inorganic

Best explanation: CLAY BINDERS COME under the category of inorganic binders. Clay binders are basically known to provide the casts with some good amount of binding properties and optimum moisture contents.

Correct option is (d) 60 – 90 SECONDS

To elaborate: A CENTRIFUGAL muller takes around 60 seconds to 90 seconds to get the core ingredients mixed properly, whereas a NORMAL muller takes about 4 MINUTES for mixing the ingredients.

Correct CHOICE is (c) 70 kg/cm^2

The EXPLANATION is: The DRY compression strength of core sand mixture for GENERAL purpose is 70 kg/cm^2, and the dry tensile strength of the of a core sand mixture is calculated to be 17 kg/cm^2.

The correct ANSWER is (b) 3 – 6 minutes

For explanation: A NORMAL muller TAKES around 3 minutes to 6 minutes to GET the core ingredients mixed properly, whereas a centrifugal muller takes around 30 seconds to ONE minute to mix the core ingredients.

Right option is (b) False

To ELABORATE: In MAGNESIUM alloys, the water content in terms of percentage is not 10%. The AMOUNT of water in terms of percentage composition is much lower than that. The composition of water around 2%.

Correct CHOICE is (c) 3119°F

For EXPLANATION: According to the properties of granular refractories, Silica has a MELTING point TEMPERATURE of 3119°F. The melting points of silica and chamotte are CALCULATED to be almost equal.

Correct answer is (a) True

To explain I WOULD SAY: For the analysis of small size GRAINS of soil, a hydrometer test is performed in which a dispersing agent is USED which blended with water to increase its specific gravity that indicates an increase in density of liquid. It ALSO affects the variation of temperature of the liquid from the hydrometer calibration temperature.

Right ANSWER is (a) 3450°F – 4620°F

Easiest explanation: ACCORDING to the properties of granular refractories, Zircon has a melting POINT TEMPERATURE of 3450°F to 4620°F. Zircon is a kind of material which does not show much changes in physical ASPECTS on exceedingly high temperatures.

The correct option is (b) False

Easiest explanation: QUARTZ grains are generally coarse in size during analysis of quartz which is greatly AFFECTED by the solidification of quartz in the igneous rocks. The shape and surface characteristics REFLECT the mechanical and chemical effects after the releasing of grains. From chemical to MECHANICALLY controlling of shape, the transition part OCCURS between the particles of 50mm to 400mm size.

The correct choice is (B) False

For explanation: SILICA sand is most freely available, without any difficulty in ABUNDANCE. Hence, the COST of this sand is low.

The correct answer is (c) 15% – 30%

The best I can explain: In green sand, the amount of CLAY needed in terms of percentage composition is approximately in between 15% to 30% and the amount of water needed in terms of percentage composition is somewhere around 5%.

The correct choice is (d) To be able to retain the HARDENABILITY

For explanation I would SAY: Dry SAND has its strength for various purposes like, to withstand a pressure of molten metal, to withstand CORROSION forces and to be able to retain its shape. But it does not have it for being able to retain the hardenability.

Correct CHOICE is (a) True

The best I can EXPLAIN: Round grains do not have a better BOND and possess lesser strength. Round grain has higher permeability than ANGULAR strength.

The CORRECT choice is (d) ZINC

Explanation: Zinc is an alloying element and is not CONSIDERED as ADDITIVE.

Correct option is (a) 0.5%

EXPLANATION: In dry SAND mouldings of steel castings, the dextrine PERCENTAGE composition is calculated to be 0.5%. In green sands, the dextrin CONTENT is also 0.5%, which is in green sand and in dry sand, the percentage of dextrine is same.

The correct choice is (a) 0.5%

The best EXPLANATION: In green SAND mouldings of steel castings, the dextrine PERCENTAGE composition is CALCULATED to be 0.5% and the bentonite percentage in the same green sand is higher than dextrin by around 3%.

Correct option is (c) OH^–IONS

Best EXPLANATION: The OH^– ions are basically the base ions. The clay particles in electrostatic BONDING THEORY, absorb the OH^– ions because of the not SATISFIED valence bond.

Correct OPTION is (a) True

The best explanation: First the fire clay is taken to the processing PLANT and then weathered for a long PERIOD of time, depending on the type of fire clay. Freezing and melting break the clay material and results in improved plasticity. Then the clay material is crushed and dried in mechanical dryers to remove the moisture content. MOSTLY, the rotary dryers FIRED with natural gas are used for drying the fire clay.

Right answer is (C) 15%

The explanation: Bentonite is classified into 2 TYPES, namely, Sodium MONTMORILLONITE and Calcium montmorillonite.Southern bentonite also called as Calcium montmorillonite is KNOWN to have a percentage COMPOSITION 15% of quartz.

The CORRECT answer is (c) 50%

The BEST I can explain: CLAY content in LOAM sand is relatively more than that of in natural sand. Also, the amount of humid content or the levels of water too in loam sand WOULD be differing similarly. The clay content in loam sand is around 50%.

Correct answer is (b) 500°C – 600°C

To elaborate: CLAY DEAD burning is a PROCESS that needs to be taken place at a comparatively higher TEMPERATURE. The temperature at which the clay dead burning takes place is somewhere in between 500°C and 600°C.

Correct choice is (c) 3.5%

Explanation: In GREEN sand mouldings of steel castings, the dextrin percentage is quite LOWER, it is around 0.5%. The bentonite percentage COMPOSITION in green sand molding is CALCULATED to be 3.5%.

The correct option is (b) Phyllosilicates

For explanation I would say: Clay GENERALLY contains phyllosilicates which are MAINLY responsible for imparting plasticity in the clay material. It can also include other materials which impart plasticity and harden-ability when the clay is dried or fired. COMBINED phases in clay material can also contain materials that do not impart any plasticity.

Correct option is (a) True

The explanation is: SOIL is mainly made of GRAINS which size distribution estimates the particle-level forces and the inter-particle packing. HENCE, the grain size distribution plays a vital role in the soil systems. The shape of grain is classified at the three different parameters which are GLOBAL form, SURFACE features and surface roughness.

The correct choice is (c) 1063°F

Easiest explanation: It is one of the disadvantages of silica SAND, that it has its thermal EXPANSION TEMPERATURE at 1063°F. At this temperature, the VOLUME of the sand starts to INCREASE.

The correct choice is (b) Hardenability

To EXPLAIN I WOULD SAY: Flowability, GREEN strength and dry strength are few of the CHARACTERISTIC properties of moulding sand, but not hardenability.

Correct CHOICE is (d) Carsil

Best explanation: Carsil is a TYPE of patented binder. Carsil is known to be a product of foseco and is therefore called as foseco-product, while the other THREE types mentioned above are all different types of clay BINDERS.

Correct choice is (b) 20

Best EXPLANATION: In general loam sand, the moisture is found to CONTAIN a DECENTLY GOOD amount of clay content in it. A general loam sand mixture contains 20 volumes of silica, the moisture of 20% and manure 1 volume.

Right ANSWER is (B) Synthetic sand

The EXPLANATION: Natural sands are used for casting ferrous and non-ferrous metals while synthetic sands are used for casting ferrous and non-ferrous ALLOYS.

Correct option is (d) Forests

Explanation: There are a variety of SOILS which can be found in forests. But the soils found there cannot be used for casting PURPOSES. Hence forests are not a source for FINDING moulding sand, WHEREAS sea, lakes and deserts are a source of finding them.

The correct option is (b) 5.5 kg/cm^2

Explanation: There are many types of cast IRONS which have differing properties, according to the type of MANUFACTURE and the quantity of ingredients used. The BAKED TENSILE strength of light to medium size malleable IRON casts is 5.5 kg/cm^2.

The correct CHOICE is (c) 6400°F

The explanation: According to the properties of granular refractories, Carbon has a melting POINT temperature of 6400°F. AMONG all the granular refractories, the melting point of carbon is CONSIDERED to be the HIGHEST.