Continuous Assessment No 03

Stokes law is related to suspension. Stokes law describes the motion of small particles in a viscous fluid. It states that the velocity of a small spherical particle moving through a viscous fluid is directly proportional to the force acting on it and the radius of the particle, and inversely proportional to the viscosity of the fluid. This law is commonly used to calculate the settling velocity of particles in a suspension, which is important in various fields such as sedimentation, filtration, and particle separation.

In the formulation development of suspension, Stoke's diameter is important. Stoke's diameter is a measure of the particle size in a suspension. It is calculated based on the settling velocity of particles in a fluid. By determining the Stoke's diameter, the sedimentation rate and stability of the suspension can be assessed. Therefore, understanding Stoke's diameter is crucial in formulating suspensions to ensure proper particle distribution and stability.

Suspended particles become flocculated in a suspension because there are appreciable attractive forces between the particles. These attractive forces cause the particles to come together and form larger aggregates or flocs. This phenomenon occurs when the attractive forces between particles are stronger than the repulsive forces. The attractive forces can be due to various factors such as Van der Waals forces, electrostatic interactions, or chemical bonding. As a result of flocculation, the suspended particles settle more easily, leading to clearer liquid or improved separation in various processes.

The correct answer is "prevent". Brownian movement refers to the random motion of particles in a fluid due to collisions with other particles. This movement helps to prevent sedimentation, which is the process of particles settling at the bottom of a fluid due to gravity. The random motion of particles disrupts the settling process and prevents them from rapidly sinking to the bottom.

Fluctuations in the ambient temperatures can cause changes in the solubility of the solute in the solvent, leading to the formation of crystals. When the temperature decreases, the solubility decreases, causing the solute to come out of solution and form crystals. Similarly, when the temperature increases, the solubility increases, causing the crystals to dissolve. These temperature fluctuations during the storage period can promote crystal growth in suspension. The other options, such as absorption of water or presence of suspending agents, do not directly explain the observed crystal growth in suspension.

The wetting ability of a vehicle is determined by observing the contact angle. The contact angle refers to the angle formed between the liquid droplet and the surface of the vehicle. A smaller contact angle indicates better wetting ability, as the liquid spreads out more evenly on the surface. On the other hand, a larger contact angle indicates poor wetting ability, as the liquid tends to bead up and not spread out effectively. Therefore, by observing the contact angle, one can assess the wetting ability of the vehicle.

Wetting agents are used to improve the spreading and penetration of a liquid on a solid surface. In the context of suspending a hydrophobic drug, wetting agents can help to increase the drug's solubility and dispersion within the formulation. This allows the drug to be more evenly distributed throughout the suspension, enhancing its stability and effectiveness. Therefore, the use of wetting agents is a suitable explanation for the correct answer.

A structured vehicle is included in the formulation of a suspension to prevent sedimentation. Sedimentation refers to the settling down of solid particles in a suspension over time due to gravity. By incorporating a structured vehicle, which typically consists of thickening agents or stabilizers, the suspension's particles are prevented from settling and forming a sediment at the bottom. This helps maintain the uniform distribution of the solid particles throughout the suspension, ensuring its stability and effectiveness.

The sedimentation volume of an ideal suspension should be equal to one. This means that the volume of sediment formed after the suspension settles should be equal to the original volume of the suspension. In an ideal suspension, the particles are evenly dispersed and do not settle too quickly or too slowly. Therefore, when the suspension settles, it should form a compact sediment without any excess volume or loss of volume.

Rheological evaluation is used to compare different suspensions. Rheology is the study of the flow and deformation of materials, and rheological evaluation involves measuring the viscosity, elasticity, and other properties of suspensions. By comparing these properties, one can determine the differences in flow behavior and stability between different suspensions. Therefore, rheological evaluation is the appropriate test for comparing different suspensions.