Homework SourseWeight of a porous sample is 325 g when wet and 315 g when d
Weight of a porous sample is 325 g when wet and 315 g when dry. The sample in the suspended condition weighs 200 g. Apparent porosity for this sample is {(W_w - W_d)/(W_w - W_s)} times 100 12% 30% 20% 10% Bulk density in the previous question is [B = W_d[(W_w - W_s]] 2.52 4.0 5.0 4.6 What is the true porosity of the sample in questions 23 and 24 if density of the sample is 5.6? [rho - B)/rho] times 100 25% 35% 45% 55% Consolidation in ceramics is done by Sintering Firing Both A and B None of above Which ceramic materials show lowest coefficient of Thermal Expansion(CTE) ZrO_2 and Al_2O_3 Diamond and BN TiO_2 and Mullite SiC and Al_2O_3 Acidic refractories contain both MgO and Al_2O_3 SiO_2 and Al_O_3 Chromite and magnesite MgO and SiO_2 polymerization of thermosets is done by Addition mechanism Vulcanization mechanism Condensation mechanism None of the above Byproduct forms in which one of the following polymerization mechanisms? Addition mechanism Vulcanization mechanism Condensation mechanism None of the above Mers of Teflon is given as None of the above PVC is_, and has high_a thermoplastic ductility a thermoset-strength an elastomer-ductility a composite-strength 
Solution
28.(c) Sintering and firing are the same thing.
30. (b)Acidic refractories consist of mostly acidic materials like alumina (Al2O3) and silica (SiO2). They are generally not attacked or affected by acidic materials, but easily affected by basic materials. They include substances such as silica, alumina, and fire clay brick refractories.
31.(c) Condensation polymerization, a form of step-growth polymerization, is a process by which two molecules join together, resulting in loss of small molecules which are often water.
32.(c) Byproduct is water
33.(c)
34.(a)
