College

8. Pick out the wrong statement:

a. High early strength cements are made from materials having a high silica-to-lime ratio.
b. The function of gypsum in cement is to enhance its initial setting rate.
c. Acid-resistant cements are known as silicate cement.
d. The major component of greyish Portland cement is tricalcium silicate.

9. Among the following compounds, which one is recycled in the Solvay process during the production of [tex]Na_2CO_3[/tex]?

a. NaCl
b. CO₂
c. NH₃
d. CaCO₃
e. B and C

10. The last step of the Solvay process is:

a. Preparation of ammoniacal brine
b. Carbonation
c. Preparation of carbon dioxide and slaked lime
d. Recovery of ammonia

11. The third step of the Solvay process is:

a. Preparation of ammoniacal brine
b. Carbonation
c. Filtration
d. Calcination

12. One of the following is the most common nitrogen-based fertilizer:

a. Anhydrous ammonia
b. Urea
c. Urea-ammonium nitrate (UAN) solutions
d. All

13. Which one of the following is the most important chemical group of herbicides?

a. Chlorophenoxy acids such as 2,4-D
b. Organic phosphorus chemicals such as glyphosate
c. Amides such as alachlor and metolachlor
d. All of the above

14. Which one of the following is a basic chemical or manufacturing product produced in Ethiopia from the local raw materials available?

a. Sugar
b. Cement
c. Soaps and detergent
d. Caustic soda
e. All of the above

Answer :

Final answer:

The incorrect statement regarding cement is option b, which suggests gypsum enhances the initial setting rate. The correct role of gypsum is to delay the setting time. In subsequent questions about the Solvay process and fertilizers, key processes and products were identified correctly as well.


Explanation:

Identifying Incorrect Statements

Let's examine the statements presented in the question:

  1. a. High early strength cements are made from materials having high silica to lime ratio.
  2. b. The function of gypsum in cement is to enhance its initial setting rate.
  3. c. Acid resistant cements are known as silicate cement.
  4. d. Major component of greyish Portland cement is tricalcium silicate.

Evaluation of Each Statement

1. Statement a is actually correct. High early strength cements do rely on a high silica to lime ratio to achieve rapid hardening.

2. Statement b is incorrect. Gypsum is added to cement specifically to slow the setting time and prevent flash setting, not to enhance initial setting rate.

3. Statement c is also incorrect. Acid resistant cements are typically known as 'high alumina cement' rather than silicate cement.

4. Statement d is correct. The major component of grey Portland cement is indeed tricalcium silicate.

Conclusion: The wrong statement in this context is b, as gypsum's role is to prolong setting time.

Understanding the Solvay Process

Question 9

Among the given choices, b. CO₂ and c. NH3 are recycled during the Solvay process of producing sodium carbonate. Therefore, the answer is e. B and C.

Step Order in Solvay Process

For questions 10, 11, and 12:

  1. Question 10: The last step of the Solvay process is b. carbonation.
  2. Question 11: The third step is a. preparation of ammonical brine.
  3. Question 12: One of the most common nitrogen-based fertilizers is d. all of the above, as anhydrous ammonia, urea, and UAN solutions are all widely used fertilizers.

Herbicide and Product Queries

In Question 13, all options, a., b., c., are significant groups of herbicides, so the answer is d. all of the above.

For Question 14 regarding Ethiopian production, e. All of the above indicates that Ethiopia produces sugar, cement, and soaps/detergents among other products.


Learn more about Cement and Chemical Processes here:

https://brainly.com/question/37136854


Other Questions