Explanation

Avogadro's number represents the number of particles (atoms, molecules, or formula units) in one mole of a substance

Its approximate value is 6.022 × 10²³

Explanation

STP is defined as 1.00 atm and 0°C, or 273 K.

One mole of a gas at STP has a volume of 22.4 liters.

Explanation

Limestone consists of calcium carbonate,

which has the chemical formula CaCO3.

Calcium carbonate is a chemical compound.

It is a common substance found in rocks as the minerals calcite.

Explanation

Complete combustion of a hydrocarbon (like methane or fuel) in the presence of sufficient oxygen produces carbon dioxide and water, releasing energy.  

Example reaction:  

CH₄ + 2O₂ → CO₂ + 2H₂O + heat

Explanation

Efficiency of a machine is never 100% because some energy is always lost due to friction between moving parts, heat, or sound.

This reduces the amount of useful output energy.

Explanation

Foam is used in fluid oil (flammable liquid) fire extinguishers because:  

- It floats on the surface of the burning liquid.  

- It cuts off oxygen supply, smothering the fire.  

- Water or sand can spread the oil, worsening the fire.

Explanation

The chemical equation for this reaction is:

N₂(g) + 3H₂(g) → 2NH₃(g) 

Reactants: Nitrogen gas (N₂) and hydrogen gas (H₂). 

Product: Ammonia gas (NH₃). 

Process: This reaction is typically carried out under high pressure and temperature using a catalyst, forming the basis of the industrial Haber process for ammonia production. 

Explanation

Absolute Pressure = Gauge Pressure + Atmospheric Pressure  

Here:  

- Gauge Pressure = 50 psi  

- Atmospheric Pressure ≈ 14.7 psi  

So, Absolute Pressure = 50 + 14.7 = 64.7 psi 

Explanation

Formula: CH₄N₂O

Molar mass: 60.06 g/mol

Soluble in: Water, Glycerol, Ethanol

Density: 1.32 g/cm³

3D model (JSmol): Interactive image

Appearance: White solid

Explanation

Urea, also called carbamide

Formula: CH₄N₂O

Molar mass: 60.06 g/mol

Soluble in: Water, Glycerol, Ethanol

Density: 1.32 g/cm³

3D model (JSmol): Interactive image

Appearance: White solid