1. The gas-solid chromatography is ______________ chromatography as per basic principle involved.
a) Exclusion
b) Ion-exchange
c) Adsorption
d) Absorption
Explanation: The gas-solid chromatography is adsorption chromatography as per basic principle involved as the gas molecules are adsorbed on the solid surface.
2. A proper solvent that is passed through the column for elution so that separated components can be collected is called ____________
a) Adsorbent
b) Buffer solution
c) Mobile phase
d) None of the mentioned
Explanation: A proper solvent that is passed through the column for elution so that separated components can be collected is called buffer solution. The eluate is the mobile phase leaving the column. The eluent is the solvent that carries the analyte.
3. The relative solubility of solute in both the phases determines the ____________
a) Rate of movement of solvent
b) Rate of disappearance of solvent
c) Rate of movement of solute
d) Rate of disappearance of solute
Explanation: The relative solubility of solute in both the phases determines the rate of movement of solute as solute is added to the solution.
4. If the mobile phase is gas, movement of solute is determined by its ____________
a) Boiling point
b) Melting point
c) Solubility
d) Volatility
Explanation: If the mobile phase is gas, movement of solute is determined by its volatility because gas is always measured as volatility not as solubility or melting point or boiling point.
5. Why Gypsum is added after calcination in the manufacture of Portland cement?
a) To prevent flash setting
b) To improve the quality of cement
c) To increase the lime saturation factor
d) None of the mentioned
Explanation: Gypsum is added after calcination to prevent the flash setting and it acts as a retarder
6. Who is recognized as the “Father of the modern Portland cement industry”?
a) Emil Abderhalden
b) Richard Abegg
c) Peter Agre
d) William Aspdin
Explanation: William Aspdin is recognized as the “Father of the modern Portland cement industry”. Portland cement is the most common type of cement in general use around the world, used as a basic ingredient of concrete, mortar, stucco, and most non-speciality grout.
7. All portland cements are hydraulic cement because they ___________
a) Set and harden in the absence of water
b) Set and harden in the presence of water
c) Do not harden after mixing water
d) None of the mentioned option
Explanation: All portland cements are hydraulic cements because they set and harden under water. This cement not only hardens by reacting with water but also forms a water-resistant product. Portland cement is the most common type of cement in general use around the world, used as a basic ingredient of concrete, mortar, stucco, and most non-speciality grout.
8. The percentage composition of alumina in Portland cement is ___________
a) 60-69
b) 17-25
c) 3-8
d) 2-4
Explanation: The percentage composition of alumina in portland cement is 3-8 %. Portland cement clinker is a hydraulic material which shall consist of at least two-thirds by mass of calcium silicates, the remainder consisting of aluminium and iron-containing clinker phases and other compounds.
9. Which compound causes the cement efflorescent, if present in excess?
a) Iron oxide
b) Alkali oxide
c) Sulphur trioxide
d) Lime
Explanation: Alkali oxides causes cement efflorescent if present in excess. The alkali metals react with oxygen to form several different compounds: suboxides, oxides, peroxides, superoxides, and ozonides.
10. Which compound imparts grey color, strength and hardness to the portland cement?
a) Iron oxide
b) Alumina
c) Magnesium oxide
d) Silica
Explanation: Iron oxide imparts grey color, strength and hardness to the portland cement.