General Q&A for Class 12 · Page 189
5,215 free answers in General for Class 12 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- GeneralClass 12All
Why do farmers spray ammonia on their fields?
Farmers apply anhydrous ammonia (a concentrated liquid form) directly to soil as an efficient nitrogen fertilizer. Nitrogen is essential for plant growth and protein synthesis. This method is cost-effective and provides plants with readily available nitrogen, promoting vigorous crop growth and higher yields.
- GeneralClass 12All
Why do fishing boats carry ammonia?
Commercial fishing vessels use ammonia in refrigeration systems to preserve catch at sea. Ammonia is an efficient, powerful refrigerant that can maintain the ultra-low temperatures needed to freeze fish quickly and keep them fresh during long voyages. It's preferred for its effectiveness and relatively low cost.
- GeneralClass 12All
How is ammonia used in cooking?
Ammonia is used in food processing as a pH regulator and leavening agent. Ammonium carbonate and ammonium bicarbonate are used in baking certain traditional cookies and crackers to create a light, crispy texture. In Scandinavian cuisine, it's used in making flatbreads and holiday cookies like speculaas.
- GeneralClass 12All
Why do US foods use ammonia?
Food-grade ammonia compounds (like ammonium hydroxide) are used in small amounts as processing aids to control acidity and kill bacteria in certain meat products. The FDA approves these uses as "generally recognized as safe" when used properly. The ammonia evaporates during processing, leaving minimal residue in the final product.
- GeneralClass 12All
What is the most effective homemade cleaner?
While ammonia-based cleaners are effective for cutting grease and removing stains, a combination of white vinegar and water (never mixed with ammonia) is often considered one of the best all-purpose homemade cleaners. For tougher jobs, baking soda paste works well. The "most effective" cleaner depends on the specific cleaning task and surface type.
- GeneralClass 12All
What is the smell of ammonia?
Ammonia has a sharp, pungent, and suffocating odor that's often described as similar to cleaning products or cat urine. The smell is highly distinctive and can be detected at very low concentrations (around 5 parts per million). Many people find it unpleasant and irritating to the nose and throat.
- GeneralClass 12All
What is the cheapest way to produce ammonia?
The Haber-Bosch process remains the most economical method for large-scale ammonia production, using natural gas as a hydrogen source. However, costs vary based on energy prices and feedstock availability. Emerging technologies using renewable energy and water electrolysis are being developed but aren't yet cost-competitive at scale.
- GeneralClass 12All
What is the largest source of ammonia?
Industrial production through the Haber-Bosch process is the largest source of ammonia globally, producing over 170 million tons annually. This process combines nitrogen from the air with hydrogen (typically from natural gas) under high pressure and temperature. Naturally, bacterial decomposition of organic matter is the primary source in ecosystems.
- GeneralClass 12All
How is ammonia made naturally?
Ammonia is produced naturally through the breakdown of organic matter containing nitrogen. Bacteria in soil decompose dead plants, animals, and waste materials, releasing ammonia as part of the nitrogen cycle. It's also produced in smaller amounts by certain bacteria that fix atmospheric nitrogen and through volcanic activity.
- GeneralClass 12All
What is the pH of ammonia?
Ammonia is basic (alkaline) with a pH typically ranging from 11 to 12 when dissolved in water. Pure ammonia gas doesn't have a pH, but when it dissolves in water to form ammonium hydroxide, it creates an alkaline solution that can neutralize acids.
- GeneralClass 12All
What is NH₄₂O called?
The correct formula you're likely referring to is (NH₄)₂O, which is ammonium oxide. However, this compound is unstable and rarely exists in pure form. You might also be thinking of ammonia water (aqueous ammonia), which is ammonia dissolved in water.
- GeneralClass 12All
Is NH₄ ammonia or NH₃?
NH₃ is ammonia, while NH₄⁺ (ammonium) is the ionic form that results when ammonia accepts a proton. When ammonia dissolves in water, it can form ammonium ions (NH₄⁺), but the pure compound ammonia itself is always NH₃. The two are related but chemically distinct.
- GeneralClass 12All
What are the 3 series circuit rules?
Current is constant: The same current flows through all components (I_total = I₁ = I₂ = I₃) Voltage divides: Total voltage equals the sum of individual voltage drops (V_total = V₁ + V₂ + V₃) Resistance adds: Total resistance is the sum of all resistances (R_total = R₁ + R₂ + R₃) These rules make series circuits predictable and easy to analyze.
- GeneralClass 12All
What is LV current?
LV stands for Low Voltage current, typically referring to electrical systems operating below 1000V AC or 1500V DC. In residential and commercial contexts, LV usually means: Household circuits: 120V-240V Safety considerations: Requires less insulation than high voltage Common applications: Lighting, appliances, electronics, and small motors LV systems are safer to work with but require larger wire sizes for high-power applicat
- GeneralClass 12All
How do you derive the formula V = IR?
The derivation comes from the definition of resistance: Resistance is defined as: R = V/I (the ratio of voltage to current) Multiply both sides by I: R × I = V Rearrange: V = I × R (or V = IR) This mathematical relationship was discovered experimentally by Georg Ohm in 1827, showing that voltage and current are proportional for most conductors at constant temperature.
- GeneralClass 12All
What is the basic formula of ammonia?
The basic chemical formula of ammonia is NH₃, which consists of one nitrogen atom bonded to three hydrogen atoms. This is a simple compound that exists as a colorless gas at room temperature with a distinctive pungent odor.
- GeneralClass 12All
What is the formula a = (v - u)/t?
This is a kinematics formula from physics, not directly related to electrical circuits: a = acceleration v = final velocity u = initial velocity t = time It calculates the rate of change of velocity. While this uses similar variable notation to electrical formulas, it's from mechanics, not electricity.
- GeneralClass 12All
How do you solve distance-rate-time (d = rt) problems?
This is another non-electrical formula (d = distance, r = rate/speed, t = time). However, the solving approach is similar to Ohm's Law: To find distance: d = r × t To find rate: r = d/t To find time: t = d/r The parallel with V = IR is clear: both involve three variables where knowing two allows you to calculate the third.
- GeneralClass 12All
How to calculate V_max value?
. V_max (maximum voltage) depends on the context: For AC circuits: V_max = V_rms × √2 ≈ V_rms × 1.414 Example: Household 120V AC has V_max ≈ 170V For DC circuits: V_max is simply the peak supply voltage For capacitors: V_max is the breakdown voltage rating Always refer to component specifications and circuit requirements when determining maximum volta
- GeneralClass 12All
What is the formula V = RW?
This appears to be a variation notation, but the standard formula is V = IR (voltage = current × resistance). If you're seeing V = RW in a specific context: W might represent current (though I is standard) It could be from a different field (like V = ωR for angular velocity) Always verify the context and variable definitions For basic circuit analysis, stick with V = IR as the standard form of Ohm's Law