Which of the following substances is commonly used in fertilizers?

• A. NH_3 (ammonia)
• B. H_2SO_4 (sulfuric acid)
• C. NaCl (sodium chloride)
• D. C_6H_{12}O_6 (glucose)

Answer: (A)

Verified step by step guidance

1. Understand the role of fertilizers: Fertilizers provide essential nutrients to plants, mainly nitrogen (N), phosphorus (P), and potassium (K), which are crucial for plant growth.
2. Identify the chemical composition of each substance: NH_3 (ammonia) contains nitrogen, H_2SO_4 (sulfuric acid) is an acid with sulfur and oxygen, NaCl (sodium chloride) is common salt, and C_6H_{12}O_6 (glucose) is a sugar molecule.
3. Recall that nitrogen is a key nutrient in fertilizers because it is a major component of amino acids and proteins in plants, promoting healthy growth.
4. Recognize that ammonia (NH_3) is a common nitrogen source in fertilizers, often used directly or as a precursor to other nitrogen-containing fertilizers like ammonium nitrate or urea.
5. Conclude that among the given options, NH_3 (ammonia) is the substance commonly used in fertilizers due to its nitrogen content and role in plant nutrition.