Live practice

In cis-hex-2-ene the larger groups lie on the same side of C=C, producing a net dipole; in trans they lie opposite and dipoles cancel more effectively.

The nitro group withdraws electron density by the −I effect through sigma bonds and disperses the negative charge.

Writing water on both sides reveals the actual source and destination of oxygen atoms. Isotopic labelling with ¹⁸O can trace those atoms through the reaction.

If 2x=0.0518 mol NOBr forms, x=0.0259 mol; subtract 2x NO and x Br₂ from their initial amounts.

Convert aluminium mass to moles and use q=nCmΔT.

Greater bond order means more shared electron density between nuclei, normally giving a shorter bond and requiring more energy to break it.

An isolated atom has no sharp boundary. Atomic radius is therefore inferred from internuclear distances in bonded atoms. Ionic radius is the effective radius assigned to an ion in a crystal from measured interionic distances.

Use Einstein's photoelectric equation E=φ+Kmax and Kmax=mv²/2.

Use the abundance-weighted mean of the two isotopic molar masses.

Principle and reasoning. Work from the governing physical relation and apply it to every stated part.

For a mass–spring oscillator, ω=sqrt(\(\frac{k}{m}\)), a_max=ω²A and v_max=ωA.