Explanation

• Potassium chloride (KCl) is a strong electrolyte that dissociates almost completely into K⁺ and Cl⁻ ions in water.
• Potassium hydroxide (KOH) also dissociates completely, adding more K⁺ ions to the solution.

Last verified on 27-10-2026

Explanation

• A sodium atom produces a line spectrum when its electrons move between specific, quantized energy levels and emit or absorb photons of definite wavelengths.
• Each element has a characteristic line spectrum because its electrons have a unique set of energy levels.

Last verified on 27-10-2026

Explanation

• Hydrogen fluoride (HF) has a very high ionic character because fluorine is much more electronegative than hydrogen.
• Its dipole moment is approximately 1.82 debye (D), which is greater than that of hydrogen chloride (HCl), approximately 1.08 D, and hydrogen disulphide (H₂S), approximately 0.97 D.
• Dipole moment depends on both the magnitude of separated charges and the distance between them.
• HF has a particularly strong bond polarity due to the large electronegativity difference between hydrogen and fluorine.

Last verified on 27-10-2026

Explanation

• Sodium carbonate forms a basic solution in water because it is a salt of a strong base (NaOH) and a weak acid (H₂CO₃).
• Carbonate ions react with water to produce hydroxide ions (OH⁻), increasing the pH above 7.

Last verified on 27-10-2026

Explanation

• Chromium has atomic number 24, so it has 24 electrons.
• Its most stable electronic configuration is [Ar] 3d⁵ 4s¹.
• The half-filled 3d subshell (3d⁵) provides extra stability.

Last verified on 27-10-2026

Explanation

• The electronic configuration 4d¹⁰ 5s² 5p⁵ belongs to iodine (I), which is a halogen with seven valence electrons.
• Iodine can gain or lose electrons during chemical reactions, so it participates in oxidation-reduction (redox) reactions.
• In a redox reaction, oxidation and reduction occur together through the transfer of electrons or changes in oxidation states.

Last verified on 27-10-2026

Explanation

Oxidation number of Cr in Na2Cr2O7:

Let oxidation number of Cr = x

2(Na) + 2(Cr) + 7(O) = 0

2(+1) + 2(x) + 7(-2) = 0

2 + 2x -14 = 0

2x = 12

x = +6

Last verified on 25-10-2026

Explanation

• Antimony is a chemical element with the symbol Sb and atomic number 51.
• The symbol Sb comes from the Latin name Stibium.
• Antimony is a metalloid used in alloys, flame-retardant materials, and some semiconductor applications.

Additional information:

• Au — Gold: Atomic number 79.
• Ag — Silver: Atomic number 47.
• Fe — Iron: Atomic number 26.
• Na — Sodium: Atomic number 11.
• K — Potassium: Atomic number 19.

Last verified on 25-10-2026

Explanation

• Hess's law states that the total enthalpy change of a chemical reaction is the same regardless of whether the reaction takes place in one step or several steps.
• Enthalpy change depends only on the initial reactants and final products, not on the pathway followed by the reaction.
• The law is based on the fact that enthalpy is a state function, meaning its value depends on the initial and final states.

Last verified on 25-10-2026

Explanation

• The addition of HCl to propene is an electrophilic addition reaction.
• The H⁺ ion attacks the double bond first, forming a more stable carbocation intermediate.

Last verified on 25-10-2026