Explanation

Potassium is more reactive than Sodium in reactivity series.

So potassium displaces sodium from NaCl:

2K + 2NaCl -> 2KCl + 2Na

And in water it also reacts:

2K + 2H2O -> 2KOH + H2

So it is a Displacement reaction.

Last verified on 01-11-2026

Explanation

• The reactivity of alkali metals increases down Group 1 of the periodic table.
• Potassium reacts more vigorously with cold water than lithium and sodium.
• The reaction produces potassium hydroxide and hydrogen gas, releasing heat that may ignite the hydrogen.

Last verified on 01-11-2026

Explanation

• 6.02 × 10²³ is Avogadro's number, which represents one mole of particles.
• One mole of water contains 6.02 × 10²³ water molecules and has a mass of approximately 18 grams.

Last verified on 01-11-2026

Explanation

• One gram molecular mass means molecular mass expressed in grams.
• One mole of water H2O has mass 18 grams, equal to its molecular mass in grams.
• One mole of water contains 6.022 x 10^23 molecules.

Last verified on 01-11-2026

Explanation

• An empirical formula represents the simplest whole-number ratio of atoms of each element in a compound.
• For example, the molecular formula of glucose is C₆H₁₂O₆, while its empirical formula is CH₂O.

Additional information:

• The molecular formula shows the actual number of atoms in a molecule.
• Empirical formula shows their simplest ratio.

Last verified on 01-11-2026

Explanation

• The Law of Mass Action was proposed by Guldberg and Waage in 1864.
• It states that the reaction rate is proportional to the product of the active concentrations of the reactants, each raised to a power specified by the reaction equation.
• For an elementary reaction, the rate expression follows directly from the stoichiometric coefficients.

Last verified on 01-11-2026

Explanation

• Active mass refers to the effective concentration of a substance taking part in a chemical reaction.
• It is commonly expressed in moles per cubic decimetre (mol/dm³).
• Active mass is used in the law of mass action to express the relationship between reactant and product concentrations.

Last verified on 01-11-2026

Explanation

• The heat of reaction depends on the physical states of reactants and products, the amount of substance involved, and the temperature.
• A catalyst changes the rate of a chemical reaction but does not change the overall enthalpy change.
• Therefore, the heat evolved or absorbed does not depend on the presence of a catalyst.

Last verified on 01-11-2026

Explanation

• Hydrogen bonding is an intermolecular attraction involving hydrogen bonded to highly electronegative atoms, usually nitrogen, oxygen, or fluorine.
• It occurs between molecules.
• Water, ammonia, and hydrogen fluoride can form hydrogen bonds.

Last verified on 01-11-2026

Explanation

• A Crookes tube contains gas at a very low pressure, approximately 0.001 mm of Hg.
• When a high voltage is applied, cathode rays produce a brilliant green fluorescence on the glass wall of the tube.
• This glow is caused by the impact of cathode rays on the glass.

Last verified on 01-11-2026