Explanation

CH₃Br molecular ion peaks come from bromine isotopes.  

Br has 2 stable isotopes: ⁷⁹Br ≈ 50.7% and ⁸¹Br ≈ 49.3% → basically 1:1 ratio

So CH₃Br gives 2 M⁺ peaks:  

1) ¹²C + 3(¹H) + ⁷⁹Br = 12 + 3 + 79 = m/z 94

2) ¹²C + 3(¹H) + ⁸¹Br = 12 + 3 + 81 = m/z 96

Because the isotopes are ~equal in nature, the two peaks are equal size/height.

Last verified on 05-06-2026

Explanation

• At constant volume, ΔE = q.
• No work is done because volume does not change.
• Therefore, all heat supplied changes the internal energy.
• This follows the First Law of Thermodynamics.

Last verified on 05-06-2026

Explanation

• SF₆ has F–S–F bond angles of 90° and 180°.
• It has an octahedral geometry.
• Six fluorine atoms are arranged symmetrically around sulfur.
• Adjacent F atoms make 90°, opposite F atoms make 180°.

Last verified on 05-06-2026

Explanation

• Fe³⁺ has the greatest magnetic moment among the given ions.
• Magnetic moment depends on the number of unpaired electrons.
• More unpaired electrons mean stronger paramagnetism.
• Fe³⁺ contains 5 unpaired electrons.

Last verified on 05-06-2026

Explanation

• In Na₄[Co(C₂O₄)₃], cobalt has coordination number 6.
• Each oxalate (C₂O₄²⁻) is a bidentate ligand.
• Three oxalate ligands provide 6 coordination sites.
• Oxidation state of Co is +3.

Last verified on 05-06-2026

Explanation

• SO₂ is a polar molecule.
• It has a bent (angular) shape which creates dipole moment.
• The dipole moments do not cancel each other.
• Therefore, it shows a net dipole moment (5.33 × 10⁻³⁰ cm given).

Last verified on 05-06-2026

Explanation

Use Graham’s Law of effusion: rate ∝ 1/√M  

And time ∝ √M since time = 1/rate

t₂ / t₁ = √(M₂ / M₁)

Molar mass: He = 4 g/mol, O₂ = 32 g/mol  

t_He = 5 s

t_O₂ = 5 × √(32 / 4) = 5 × √8 = 5 × 2.828 ≈ 14.1 s.

Last verified on 05-06-2026

Explanation

• Cholesteryl benzoate is an example of a liquid crystal.
• It shows properties of both liquids and solids.
• It exhibits ordered molecular arrangement like crystals.
• It changes phases with temperature.

Last verified on 05-06-2026

Explanation

• The free radical substitution reaction of CH₄ with Cl₂ is a zero-order reaction.
• Its rate does not depend on the concentration of reactants under steady conditions.
• The reaction proceeds via chain mechanism (initiation, propagation, termination).
• So overall observed order is zero.

Last verified on 05-06-2026

Explanation

Molality m = moles of solute / kg of solvent

For 60% w/w solution, take 100 g solution:

1) Solute: 60 g ethylene glycol C₂H₆O₂  

Molar mass = 2(12) + 6(1) + 2(16) = 62 g/mol  

Moles EG = 60 / 62 ≈ 0.9677 mol

2) Solvent: 40 g water = 0.040 kg

3) Molality

m = 0.9677 mol / 0.040 kg ≈ 24.2 mol/kg

Last verified on 05-06-2026