All the given pairs can undergo double displacement reactions.

2H2 + O2 → 2H2O. 1 mole of water weighs 18 g, so 2 moles produce 36 g. Thus, 18 g of water is produced from 1 mole of O2.

2 moles of H2 and 1 mole of O2 produce 2 moles of H2O. The molar mass of water is 18 g/mol, so 2 moles produce 36 g.

From 2 moles of Fe, 2 moles of FeCl3 are produced. Therefore, from 4 moles of Fe, 4 moles of FeCl3 are produced.

The balanced equation for the combustion of propane is C3H8 + 5O2 → 3CO2 + 4H2O.

The chemical formula for sulfuric acid is H2SO4, which consists of two hydrogen atoms, one sulfur atom, and four oxygen atoms.

The conjugate base of sulfuric acid (H2SO4) is HSO4-.

Adding a base to hydrochloric acid will neutralize it, resulting in an increase in pH.

Adding a base to an acidic solution increases the pH, making it less acidic.

The electron configuration of chlorine is 1s² 2s² 2p⁶ 3s² 3p⁵, filling up to the 3p subshell.

Oxygen has 8 electrons, and its electron configuration is 1s² 2s² 2p⁴.

The IUPAC name for CH3-CH2-COOH is propanoic acid, as it has three carbon atoms in the longest chain.

Liquids have a definite volume and take the shape of their container, while gases have neither a definite shape nor volume.

The thermal decomposition of calcium carbonate produces calcium oxide (CaO) and carbon dioxide (CO2).

The oxidation of a primary alcohol typically produces a carboxylic acid.

Non-metals are generally brittle in solid form and do not exhibit metallic luster.

Temperature is the primary factor that affects the state of matter by influencing particle energy.

The complete combustion of propane produces carbon dioxide (CO2) and water (H2O) as primary products.

The reaction produces sodium chloride, carbon dioxide, and water.

Solids have a definite shape and volume due to closely packed particles.

Aluminum is widely used in structural components due to its strength-to-weight ratio.

The reaction between HCl and NaOH produces sodium chloride (NaCl) and water (H2O).

Sodium reacts with chlorine to form sodium chloride (NaCl).

Mixing equal volumes of 0.1 M HCl and 0.1 M NaOH results in a neutral solution with pH = 7.

The reaction CaCO3 → CaO + CO2 is a decomposition reaction, where one compound breaks down into two products.

An acid reacting with a base results in a neutralization reaction, producing salt and water.

Lead is commonly used in lead-acid batteries due to its ability to store electrical energy.

Titanium is known for its high resistance to corrosion, making it suitable for various applications.

Aluminum is primarily used in aircraft construction because of its favorable strength-to-weight ratio.

Chromium is added to iron to produce stainless steel, enhancing its corrosion resistance.