Particle Size Analysis ASTM D422

Explanation
The sedimentation cylinder should have a capacity of 1000 ml. This is because a larger capacity allows for a larger sample size to be tested, providing a more accurate representation of the sedimentation process. Additionally, a larger cylinder allows for more precise measurements to be taken, reducing the margin of error in the experiment. Therefore, a 1000 ml capacity is ideal for sedimentation testing.

Explanation
The thermometer used for ASTM D422 shall be readable to 0.5 c. This means that the thermometer should have markings or divisions that allow for measurements to be read with an accuracy of 0.5 degrees Celsius. This level of readability ensures that the temperature measurements taken during the ASTM D422 test are precise and reliable.

Explanation
Sodium hexametaphosphate is the dispersing agent in this scenario. Dispersing agents are used to prevent the clumping or aggregation of particles in a solution. Sodium hexametaphosphate is a commonly used dispersing agent due to its ability to bind to particles and keep them separate. Sodium hydroxide and sodium bicarbonate are not typically used as dispersing agents, making sodium hexametaphosphate the correct answer.

Explanation
The hygroscopic moisture refers to the amount of moisture that a substance can absorb from the surrounding environment. In this case, the correct answer suggests that the substance should be able to absorb a range of 10g to 15g of moisture.

Explanation
The hygroscopic moisture needs to be dried back to a constant weight at a temperature of 110 +/- 5 degrees Celsius. This means that the moisture should be heated to a temperature within the range of 105 to 115 degrees Celsius in order to remove all the moisture and reach a stable weight.

Explanation
The coarse sieve shall be performed on the Plus #4 fraction of the sample. This means that particles larger than the size of the openings in the #4 sieve will be retained on the sieve, while smaller particles will pass through. The #4 sieve has larger openings compared to the #10, #16, and #8 sieves, indicating that it is designed to separate larger particles from the sample.

Explanation
If the material is sandy, it means that the sample being measured by the hydrometer contains sand particles. Sand is relatively dense and heavy, so it would contribute to the overall weight of the sample. Therefore, the weight of the sample for the hydrometer would be 100 g.

Explanation
The correct answer is 125 ml. This amount of dispersing agent is added to the sample for the soaking period.

Explanation
The sample is required to soak in the dispersing agent for 16 hours. This duration allows for proper dispersion of the sample particles within the agent, ensuring accurate and reliable results. A longer soaking time allows for better dispersion and avoids any potential errors or inconsistencies in the analysis.

Explanation
The sample is turned upside down and back for 60 seconds. This duration of time allows for proper mixing and agitation of the sample in the beaker.

Explanation
The hydrometer bubble should be placed in the soil solution 10 to 25 seconds prior to taking the reading. This allows enough time for the bubble to stabilize and for an accurate measurement to be obtained.

Explanation
The statement is suggesting that the thermometer is suspended and the temperature is recorded after each hydrometer reading. This implies that the temperature is being measured accurately and separately from the hydrometer reading. Therefore, the statement is true.

Explanation
After the final hydrometer reading, the sample is washed using a sieve with a #200 mesh size. The mesh size of a sieve refers to the number of openings per linear inch. In this case, a #200 sieve has 200 openings per linear inch, indicating that it has a fine mesh size. Washing the sample through this sieve helps to separate any remaining particles that are larger than the #200 mesh size, ensuring a more accurate and precise final measurement.