Chapter 9 Multiple Choice Questions

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. How do insects such as pond skaters stay afloat on water?

Because of high surface tension of water correct incorrect

As they can swim correct incorrect

Because they are less dense than water correct incorrect

None of the above reasons correct incorrect

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. Cohesive forces are the forces acting...

Between molecules of different materials correct incorrect

Between molecules of same material correct incorrect

Between water and glass capillary tube correct incorrect

Due to gravity correct incorrect

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. The contact angle forming between magnesium stearate and water is larger than that between lactose and water because:

Magnesium stearate is more hydrophilic correct incorrect

Magnesium stearate is more hydrophobic correct incorrect

Lactose has more surface energy correct incorrect

Both have equal hydrophilicity correct incorrect

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. Which of the following values for contact angle with water corresponds to a hydrophobic drug particle?

45° correct incorrect

120° correct incorrect

0° correct incorrect

None of the above correct incorrect

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. The Freundlich adsorption isotherm can be used to model:

Multilayer adsorption correct incorrect

Monolayer adsorption correct incorrect

Both correct incorrect

None of the above correct incorrect

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. Which of the following does not have an effect on adsorption from solution onto a solid adsorbent?

Solubility level of solute correct incorrect

Absorption capacity correct incorrect

Temperature of adsorption medium correct incorrect

Surface area of adsorbent correct incorrect

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. What is the main result of adding surfactants into a liquid composed of two immiscible phases such as oil and water?

Reduction in the interfacial tension between the phases correct incorrect

Increase in the interfacial tension between the phases correct incorrect

Catalysation of a chemical reaction between the phases correct incorrect

Nothing happens correct incorrect

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. A surfactant with a very large Hydrophile-Lipophile Balance (HLB) value (e.g. 40) is expected to function as a:

Anti-foaming agent correct incorrect

Water in oil (w/o) emulsifier correct incorrect

Oil in water (o/w) emulsifier correct incorrect

Solubility enhancer correct incorrect

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. Which of the following drug delivery systems comprises a hydrophobic core and a hydrophilic surface?

Liposomes correct incorrect

Micelles correct incorrect

Reverse micelles correct incorrect

None of the above correct incorrect

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. Measuring zeta potential is useful in determining which property of a liquid formulation?

Viscosity correct incorrect

Stability correct incorrect

Solubility correct incorrect

Particle size correct incorrect