1. Assertion (A): Chemical fertilizers are necessary for the phosphorus needs of plants.
Reason (R): One metric ton of organic manure can barely supply 2 or 3 kg of phosphorus.
From the above statement, which is correct :
(a) Both (A) and (R) are true and (R) is the correct explanation of (A).
(b) Both (A) and (R) are true but (R) is not the correct explanation of (A).
(c) (A) is true, but (R) is false.
(d) (A) is false, but (R) is true.
[U.P. Lower Sub. (Pre) 1998]
Ans. (a) Both (A) and (R) are true and (R) is the correct explanation of (A).
- Adding fertilizers to the soil helps plants grow and produce more.
- Nitrogen, Phosphorus, and Potassium are all important for plants.
- To get 1 metric ton of organic manure, only 1.5 to 3 kg of Phosphorus is obtained.
- Therefore, chemical fertilizers are needed in order for plants to get enough Phosphorus.
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2. For wheat cultivation which fertilizer is used?
(a) Nitrogen
(b) Potassium
(c) Copper
(d) Iron
[47th B.P.S.C. (Pre) 2005]
Ans. (a) Nitrogen
- Nitrogen is necessary for plants to grow.
- To cultivate wheat, nitrogen fertilizer is very essential.
- A lack of nitrogen is often the main cause of plant health issues.
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3. The element not provided by the fertilizers is –
(a) Nitrogen
(b) Hydrogen
(c) Chlorine
(d) Phosphorus
[U.P.P.C.S. (Mains) 2007]
Ans. (b) Hydrogen
- Fertilizer is something added to the ground to make it better for growing plants.
- There are 16 important elements needed for plants to grow, such as Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, Potassium, Calcium, Magnesium, Boron, Chlorine, Copper, Iron, Manganese, Molybdenum, and Zinc.
- These elements are found in the soil in the form of salts.
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4. Which one of the following is not correctly matched?
| Plant Nutrients |
Role |
| (a) Nitrogen |
Growth and Development |
| (b) Phosphorus |
Root development |
| (c) Potassium |
Regulating stomatal opening and closing |
| (d) Boron |
Disease resistance |
[U.P. R.O./A.R.O. (Pre) 2016]
Ans. (*)
- Nitrogen, Phosphorus, and Potassium are important elements for plants.
- Nitrogen helps with leaf growth and makes leaves look yellow when there is a lack of it.
- Phosphorus helps transport food and root growth.
- Potassium helps with the opening and closing of the plant’s ‘breathing holes’.
- Boron is a tiny element for plants – if there is not enough of it, it can cause problems like rotting in beets and apples.
- It also helps make plants stronger and more able to fight off diseases.
- All of these elements are essential for plants.
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5. Which one of the following fertilizers leaves maximum acidity in the soil?
(a) Urea
(b) Ammonium Sulphate
(c) Ammonium Nitrate
(d) Calcium Ammonium Nitrate
[U.P.P.C.S. (Pre) 1996]
Ans. (b) Ammonium Sulphate
- Acidic soil can reduce crop yields.
- You can tell if the soil is acidic by testing the pH, which should be below 7.
- Ammonium sulfate should not be used on acidic soil as it makes the soil even more acidic.
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6. Urea is –
(a) A nitrogen-containing organic compound
(b) A nitrogen-containing inorganic compound
(c) A plant hormone
(d) An Endergonic compound
[U.P.P.C.S. (Pre) 2017]
Ans. (a) A nitrogen-containing organic compound
- Urea is a type of organic chemical with the formula CO(NH2 )2.
- It has a lot of nitrogen, about 46.7%, which is in the form of an amide.
- It is also known as carbamide in the organic chemical industry.
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7. The percentage of nitrogen in urea is-
(a) 30%
(b) 25%
(c) 47%
(d) 60%
[U.P. Lower Sub. (Pre) 2009]
Ans. (c) 47%
- Urea, also known as Carbamide, is an organic compound made up of 46-47% nitrogen.
- It has two parts, each with a nitrogen-containing amide group.
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8. The elements present in urea are :
(a) C, H, O
(b) C, N, O
(c) C, H, N
(d) C, H, N, O
(e) None of the above / More than one of the above
[66th B.P.S.C. (Pre) 2020]
Ans. (d) C, H, N, O
- Urea, also known as Carbamide, is an organic chemical containing about 46-47% nitrogen.
- It has two parts, each made up of a nitrogen-containing group called an amide.
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9. Which form of nitrogen is available in urea?
(a) Amide
(b) Ammoniacal
(c) Nitrate
(d) Nitrite
[U.P.P.C.S. (Spl.) (Mains) 2008]
Ans. (a) Amide
- Urea (also known as Carbamide) is an organic compound with a chemical formula of CO(NH2)2.
- It contains around 46-47% nitrogen, which is found in two amide (NH2) groups.
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10. Which of the following chemical fertilizers is relatively more soluble in water at 20oC?
(a) Ammonium Sulphate
(b) Urea
(c) Diammonium phosphate
(d) Ammonium Chloride
[U.P. P.C.S. (Mains) 2017]
Ans. (b) Urea
- Urea is an organic compound that can only stay in an acidic environment.
- It got its name from a Greek word which means “urine”.
- Urea is much easier to dissolve in water than other kinds of fertilizers.
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11. How much amount of urea will be required to supply 1 kg of nitrogen?
(a) 2.0 kg
(b) 2.2 kg
(c) 2.5 kg
(d) 2.7 kg
[U.P. B.E.O. (Pre) 2019]
Ans. (b) 2.2 kg
- We know that amount of nitrogen in urea = about 46%
- Urea required for supplying 46 gm of nitrogen = 100 gm
- Urea required for supplying 1000 gm (1 kg) of nitrogen= 100/46×1000 = 2174 gm = 2.2 kg (approx.)
- Hence, about 2.2 kg of urea will be required to supply 1 kg of nitrogen.
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12. With reference to chemical fertilizers in India, consider the following statements :
1. At present, the retail price of chemical fertilizers is market-driven and not administered by the Government.
2. Ammonia, which is an input of urea, is produced from natural gas.
3. Sulphur, which is a raw material for phosphoric acid fertilizer, is a by-product of oil refi neries.
Which of the statements given above is/are correct?
(a) 1 only
(b) 2 and 3 only
(c) 2 only
(d) 1, 2 and 3
[I.A.S. (Pre) 2020]
Ans. (b) 2 and 3 only
- Urea is a main chemical fertilizer and the government has set a price for it.
- For phosphatic and potassic fertilizers, the government has implemented a Nutrient Subsidy (NBS) policy since 1.4.2010.
- Under this policy, fertilizer companies are allowed to set their own prices, while the government gives them subsidies based on nutrients.
- Ammonia is used to make nitrogenous fertilizers, including urea, and hydrogen is taken from natural gas to make ammonia.
- Hydrogen is made from thermal processes such as steam-methane reformation and partial oxidation.
- Also, in India, elemental sulphur is produced from petroleum refineries which is used to make phosphoric acid fertilizers.
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13. What can be the impact of the excessive/ inappropriate use of nitrogenous fertilizers in agriculture?
1. The proliferation of nitrogen-fixing microorganisms in soil can occur.
2. The increase in the acidity of soil can take place.
3. Leaching of nitrate to the groundwater can occur.
Select the correct answer using the code given below.
(a) 1 and 3 only
(b) 2 only
(c) 2 and 3 only
(d) 1, 2 and 3
[I.A.S. (Pre) 2015]
Ans. (c) 2 and 3 only
- Using too much nitrogen fertilizer in farming can have various bad impacts on the environment.
- Like making the soil too acidic, leaking into the groundwater, and causing an overgrowth of plants.
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14. The plants receive Nitrogen in the form of :
(a) Nitric oxide
(b) Nitrate
(c) Ammonia
(d) Nitride
[U.P. P.C.S. (Pre) 2016]
Ans. (b) Nitrate
- The most common forms of nitrogen in the soil are ammonium and nitrate.
- Plants typically take in nitrogen in the form of nitrate.
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15. Nitrogen is taken by plants in the form of :
(a) Oxide
(b) Nitrate
(c) Nitric acid
(d) Chloride
[Jharkhand P.C.S. (Pre) 2021]
Ans. (b) Nitrate
- The main nitrogen found in the ground is ammonium and nitrate.
- Plants typically take in nitrogen in the form of nitrate.
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16. Which of the following is consumed in the manufacture of urea fertilizer?
(a) Carbon dioxide
(b) Sulphur dioxide
(c) Chlorine
(d) Nitric acid
[Uttarakhand P.C.S. (Mains) 2006]
Ans. (a) Carbon dioxide
- Urea is a type of organic compound.
- It has no color, no smell, and mixes easily with water.
- It’s also very safe.
- Companies create urea from ammonia and carbon dioxide for use in different industries.
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17. Why does the Government of India promote the use of ‘Neem-coated Urea’ in agriculture?
(a) Release of Neem oil in the soil increases nitrogen fixation by the soil microorganisms
(b) Neem coating slows down the rate of dissolution of urea in the soil
(c) Nitrous oxide, which is a greenhouse gas, is not at all released into the atmosphere by crop fields
(d) It is a combination of a weedicide and a fertilizer for particular crops
[I.A.S. (Pre) 2016]
Ans. (b) Neem coating slows down the rate of dissolution of urea in the soil
- Urea is broken down when it is put in the ground by water into ammonical form and then nitrite and nitrate.
- Most plants use nitrate as a source of nitrogen.
- If the breakdown of urea is too quick, the nitrogen will go into the air and plants will not be able to get it from urea.
- To regulate this breakdown, chemical or natural agents are used, like neem oil.
- If neem oil coats the urea, it has been proven to help the release of the urea to be more gradual and help plants get more nutrients, resulting in higher yields.
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18. What percentage of phosphorus ( P 2 O5) and Nitrogen (N) is present in DAP?
(a) 10% N and 20% P 2 O5
(b) 18% N and 46% P 2 O5
(c) 30% N and 60% P 2 O5
(d) 35% N and 70% P 2 O5
[U.P.P.C.S. (Mains) 2008]
Ans. (b) 18% N and 46% P 2 O5
- DAP is a fertilizer that has a formula of (NH4 ) 2 HPO4.
- When it is dissolved in water, the average pH level is 7.5-8.
- This fertilizer is made up of 18% nitrogen and 46% P2 O5.
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19. Which one of the following is a mixed fertilizer?
(a) Urea
(b) CAM
(c) Ammonium Sulphate
(d) NPK
[I.A.S. (Pre) 1995]
Ans. (d) NPK
- NPK fertilizer is a combination of three major nutrients (Nitrogen, phosphorus, and Potassium) that plants need to grow well.
- Different proportions of these nutrients in the fertilizer can help different types of soil.
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20. Which of the following is not a chemical fertilizer?
(a) Urea
(b) Sodium Sulphate
(c) Super Phosphate
(d) Potassium Nitrate
[Uttarakhand P.C.S. (Pre) 2010]
Ans. (b) Sodium Sulphate
- Urea, superphosphate, and potassium nitrate are all types of chemical fertilizers.
- Sodium sulfate (Na2 SO4), however, is not used as a fertilizer – it is the salt version of sulphuric acid.
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21. The most popular fertilizer for foliar application is –
(a) Sodium Nitrate
(b) Urea
(c) D.A.P.
(d) Potassium Chloride
[U.P. Lower Sub. (Pre) 2015, U.P.P.C.S. (Mains) 2015]
Ans. (b) Urea
- Foliar fertilization is when you put nutrients on the leaves or needles of a plant.
- Urea is a common choice for this because it is easy to dissolve and the plant can take it in quickly and easily.
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22. ‘Humus’ is an example of –
(a) Soil structure
(b) Crystalloids
(c) Organic colloids
(d) None of the above
[U.P.R.O./A.R.O. (Pre) 2014]
Ans. (c) Organic colloids
- Humus is the organic material made from decaying plants and animals that’s found in the top layer of soil.
- It’s usually dark in color and is formed from natural breakdown of materials like leaves.
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23. The most suitable crop for green manuring is –
(a) Potato
(b) Sugarcane
(c) Sunhemp
(d) Gram
[U.P.P.C.S. (Mains) 2015]
Ans. (c) Sunhemp
- Green manure is a type of fertilizer that is made from decomposed plant material.
- It is acquired in two ways – either by growing green manure crops or by collecting green leaves and twigs from plants in wastelands, fields, and forests.
- Green manuring is when you grow plants – usually from the leguminous family – in a field and then put them back into the soil after they have grown.
- The most common green manure crops are sun hemp, dhaincha, pillipesara, cluster bean, and sesbania rostrata.
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