General Q&A for Class 12 · Page 171
5,215 free answers in General for Class 12 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- GeneralClass 12All
What is urea made from?
In the body, urea is made from ammonia and carbon dioxide through the urea cycle in the liver. Industrially, urea is synthesized by reacting ammonia with carbon dioxide under high pressure and temperature, primarily for use in fertilizers and other applications.
- GeneralClass 12All
Is CO₂ used to make urea?
Yes, carbon dioxide (CO₂) is essential for urea production. In the body's urea cycle, CO₂ combines with ammonia to form urea. Industrial urea synthesis also uses CO₂ as a key reactant with ammonia.
- GeneralClass 12All
What is DEF urea?
DEF (Diesel Exhaust Fluid) is a solution containing 32.5% urea and 67.5% deionized water. It's used in modern diesel vehicles with Selective Catalytic Reduction (SCR) systems to reduce harmful nitrogen oxide emissions.
- GeneralClass 12All
Is urea in DEF urine?
No, urea in DEF is not derived from urine. DEF uses synthetically manufactured urea that meets strict automotive-grade purity standards. It's chemically identical to natural urea but produced through industrial processes.
- GeneralClass 12All
What is another name for urea?
Urea is also known as carbamide. In medical contexts, you might see it referred to as blood urea nitrogen (BUN) when measured in blood tests. Other technical names include carbonyl diamide.
- GeneralClass 12All
What do kidneys do with urea?
The kidneys filter urea from the bloodstream and excrete it in urine. This filtration process removes waste products while retaining essential nutrients and water, helping maintain the body's chemical balance.
- GeneralClass 12All
Which organ produces urea?
The liver produces urea through a process called the urea cycle. The liver converts toxic ammonia (from protein breakdown) into urea, which is then released into the bloodstream and transported to the kidneys for elimination.
- GeneralClass 12All
Is urea NH₄⁺?
No, urea is not NH₄⁺ (ammonium ion). Urea has the formula CO(NH₂)₂, while NH₄⁺ is a positively charged ion formed when ammonia accepts a proton. These are distinct chemical compounds with different structures and properties.
- GeneralClass 12All
Is urea also uric acid?
No, urea and uric acid are two different compounds. Urea (CH₄N₂O) is the primary nitrogenous waste in mammals, while uric acid (C₅H₄N₄O₃) is the main waste product in birds and reptiles. Humans produce both, but urea is the dominant form.
- GeneralClass 12All
Is human urine a urea?
Human urine is not urea itself, but rather contains urea as one of its main components. Urine is a complex liquid mixture where urea accounts for roughly 2% of the total volume, making it the most abundant dissolved solid waste product.
- GeneralClass 12All
Is urea also called urine?
No, urea is not called urine. Urea is a specific chemical compound that is one component of urine. Urine is the liquid waste that contains urea along with water, salts, and other dissolved substances.
- GeneralClass 12All
What is 95% of urine?
Approximately 95% of urine is water. The remaining 5% consists of dissolved waste products, with urea being the most abundant solid component (about 2% of total urine), along with creatinine, uric acid, salts, and other substances.
- GeneralClass 12All
Is urea 100% nitrogen?
No, urea is not 100% nitrogen. Urea contains approximately 46-47% nitrogen by weight, along with carbon, hydrogen, and oxygen. This high nitrogen content makes urea valuable as a nitrogen-rich fertilizer in agriculture.
- GeneralClass 12All
Is NH₂CONH₂ urea?
Yes, NH₂CONH₂ is urea. This is simply another way to write the chemical formula, emphasizing the two amino groups (NH₂) attached to a central carbonyl group (CO). Both CH₄N₂O and NH₂CONH₂ represent the same compound.
- GeneralClass 12All
What makes up 95% of urine?
Water makes up roughly 95% of urine volume. This high water content allows the kidneys to dissolve and flush out waste products from the bloodstream effectively while maintaining the body's fluid balance.
- GeneralClass 12All
What is the molar mass of urea?
The molar mass of urea is approximately 60.06 g/mol. This is calculated by adding the atomic masses of all atoms in the formula: carbon (12.01) + oxygen (16.00) + nitrogen (14.01 × 2) + hydrogen (1.01 × 4) = 60.06 g/mol.
- GeneralClass 12All
What is the name of H₂NCONH₂?
H₂NCONH₂ is the chemical name for urea, also known as carbamide. This notation is yet another way to represent the molecular structure, showing the two amine groups (H₂N) bonded to a carbonyl carbon.
- GeneralClass 12All
What is the chemical formula for urea?
The chemical formula for urea is CH₄N₂O or CO(NH₂)₂. This organic compound consists of one carbon atom, four hydrogen atoms, two nitrogen atoms, and one oxygen atom. The structural formula shows a carbonyl group (C=O) bonded to two amino groups (NH₂).
- GeneralClass 12All
How to calculate Hz frequency?
To calculate frequency in Hz, use one of these methods based on available data: Method 1 - From period: f = 1/T Measure time for one cycle, divide 1 by that time Method 2 - From wave properties: f = v/λ Divide wave speed by wavelength Method 3 - From RPM: f = RPM/60 Divide rotations per minute by 60 to get Hz Method 4 - From ang
- GeneralClass 12All
How to find delta H and delta E?
These represent energy changes in chemistry and physics: ΔE (change in internal energy): ΔE = q + w q = heat added to system w = work done on system ΔH (change in enthalpy): ΔH = ΔE + Δ(PV) For reactions involving photon energy at specific frequencies: E = hf, where h is Planck's constant and f is frequency These relate to frequency when study