Explanation

• Sir James Chadwick discovered the neutron in 1932.
• He was a British physicist.
• His discovery completed the basic picture of the atomic nucleus.
• He received the Nobel Prize in Physics in 1935 for this discovery.

Additional information:

• J. J. Thomson – Electron (1897)
• Ernest Rutherford – Atomic nucleus (1911) and Proton (1917)

Last verified on 03-07-2026

Explanation

• Najibullah is the title of Hazrat Dawood (AS).
• The holy book Zaboor revealed to Hazrat Dawood (AS).
• He is buried in Israel.
• He is called caliph of Allah.
• He is mentioned in the Holy Quran for 16 times.

Last verified on 23-04-2026

Explanation

Look at the reaction: N₂ + 3H₂ → 2NH₃

For every 1 N₂ that reacts, 3 H₂ react.  

So H₂ gets used 3 times faster than N₂.

Given: H₂ is used at 1.72 mol L⁻¹ h⁻¹  

Then N₂ is used 3x slower:

Rate of N₂ = 1.72 ÷ 3 = 0.57 mol L⁻¹ h⁻¹

Last verified on 05-06-2026

Explanation

• Fatty acids are carboxylic acids with long hydrocarbon chains.
• They contain a carboxyl group (–COOH) attached to a long alkyl chain.
• They are major components of fats and oils.

Last verified on 05-06-2026

Explanation

• Oxidation of secondary alcohols produces ketones.
• Secondary alcohols have –OH group attached to a carbon bonded with two other carbons.
• During oxidation, hydrogen is removed and a carbonyl (C=O) group is formed.

Additional information:

• Primary alcohol → Aldehyde → Acid
• Secondary alcohol → Ketone (stops here)
• Tertiary alcohol → No easy oxidation

Last verified on 05-06-2026

Explanation

• sp² hybridization is used by each oxygen in carbonic acid (H₂CO₃).
• In H₂CO₃, carbon is bonded to three oxygen atoms.
• Each oxygen forms sigma bonds and has resonance involvement.
• Oxygen adopts sp² hybrid orbitals for proper bonding geometry.

Last verified on 05-06-2026

Explanation

• NMR (Nuclear Magnetic Resonance) spectroscopy depends on nuclear spin.
• Only nuclei with non-zero spin give NMR signals.
• Elements with zero nuclear spin are NMR inactive.
• Therefore, they cannot be directly detected by NMR spectroscopy.

Last verified on 05-06-2026

Explanation

Use Beer-Lambert Law: A = ε c l

Where:  

A = absorbance = 0.15  

c = concentration = 1.0 × 10⁻³ mol dm⁻³  

l = path length = 1 cm  

ε = molar extinction/absorption coefficient = ?

Rearrange: ε = A / (c × l)  

ε = 0.15 / (1.0 × 10⁻³ × 1)  

ε = 0.15 / 0.001 = 150 mol⁻¹ dm³ cm⁻¹

Last verified on 05-06-2026

Explanation

• AlCl₃ is the catalyst in Friedel–Crafts alkylation.
• It acts as a Lewis acid and generates the electrophile (R⁺).
• This electrophile attacks benzene ring in the reaction.

Last verified on 05-06-2026

Explanation

• Pure water can be obtained from seawater by distillation.
• Distillation separates water from dissolved salts and impurities.
• Seawater is heated to form water vapor.
• The vapor is then cooled and condensed into pure water.
• Therefore, distillation gives clean, salt-free water.

Last verified on 05-06-2026