Explanation

• Electronegativity is the ability of an atom to attract electrons in a bond.
• It increases across a period from left to right due to increasing nuclear charge.
• It decreases down a group because atomic size increases.
• Therefore, the correct trend is left to right in a period.

Last verified on 12-04-2026

Explanation

• Across a period, metallic character decreases from left to right.
• Magnesium is a metal, so it forms a basic oxide.
• Phosphorus and chlorine are non-metals, so they form acidic oxides.
• Therefore, Mg → basic, P → acidic, Cl → acidic oxides.

Last verified on 12-04-2026

Explanation

• Elements in the same group have similar chemical properties because they have the same number of valence electrons, not total electrons.
• They show similar reactions due to similar outer shell configuration.
• However, they differ in atomic (proton) number and mass number.
• Therefore, statement 2 and 3 are correct.

Last verified on 12-04-2026

Explanation

• A neutral salt is formed when a strong acid reacts with a strong base.
• It does not show acidic or basic nature in water.
• Its pH is approximately 7.
• It contains equal strength of acid and base ions.
• Example of neutral salt is NaCl (Sodium Chloride).

Last verified on 11-04-2026

Explanation

To get max Cr from Cr₂O₃, use the mass fraction of Cr in Cr₂O₃.

Molar mass Cr₂O₃ = 2(52) + 3(16) = 104 + 48 = 152 g/mol

Mass of Cr in 1 mol = 2(52) = 104 g

So Cr mass = 76g × (104/152) = 76 × 0.684 = 52g

Last verified on 11-04-2026

Explanation

• Coal, petroleum, and natural gas are fossil fuels formed from ancient organic matter.
• Hydrogen is a clean fuel, not formed from fossilized remains.
• It is considered a future energy source due to its high efficiency and low pollution.

Last verified on 11-04-2026

Explanation

• Electrolysis of concentrated aqueous sodium chloride (brine) involves breaking down compounds using electricity.
• Inert electrodes do not take part in the reaction.
• At the negative electrode (cathode), reduction occurs.
• Hydrogen ions are reduced instead of sodium ions in aqueous solution.
• This produces hydrogen gas at the cathode.

Last verified on 11-04-2026

Explanation

• In thermodynamics, state functions depend only on initial and final states.
• They do not depend on the path taken.
• Examples include internal energy, enthalpy, and entropy.
• Work done depends on the path of the process.
• Therefore, it is not a state function.

Last verified on 11-04-2026

Explanation

• A salt and water mixture is a homogeneous solution.
• To separate both components, we need a method that recovers water and salt separately.
• Some methods only recover one component.
• Proper separation depends on physical properties like boiling point.
• Distillation is used for complete separation of both substances.

Last verified on 11-04-2026

Explanation

• Enzymes work best at an optimum temperature.
• Temperature changes affect enzyme activity and shape.
• High temperature can damage enzyme structure.
• This reduces the enzyme’s ability to function properly.
• Enzymes are sensitive biological catalysts.

Last verified on 11-04-2026