Live practice

Write condensed structural formulae for (i) ethanoic acid(ii) a bromopentane(iii) butanone(iv) hexanal. Also state whether bromopentane has structural isomers.

Name the gas formed when a reactive metal is treated with dilute hydrochloric acid. Also write the balanced equation for iron with dilute sulphuric acid.

Why can an aqueous acid solution conduct electric current?

An offshore tower tolerates stress up to 1.0×10⁹ Pa. Check whether the static water pressure at \(3.0\,\mathrm{km}\) depth is within this limit, taking seawater density about 1.03×10³ \(\mathrm{kg\,m}\)⁻³.

Equal particles of mass m and speed v travel oppositely on parallel lines separated by d. Show their total angular momentum is independent of the chosen origin.

Decide, with reasons, whether four statements about elastic collisions, total energy, closed-loop work and inelastic-collision kinetic energy are always true.

Four vectors obey a+b+c+d=0. Test whether (a) all must vanish(b) |a+c|=|b+d|(c) |a| cannot exceed |b|+|c|+|d|(d) b+c lies in the plane/line determined by a and d.

For one-dimensional motion, judge: (a) zero speed at an instant can coexist with nonzero acceleration(b) zero speed can coexist with nonzero velocity(c) constant speed requires zero acceleration(d) positive acceleration always means speeding up.

A microscope magnifies 100 times. The observed mean width of a hair is \(3.5\,\mathrm{mm}\). Estimate its actual thickness.

Using the events A, B and C from the preceding two-dice problem, state whether each of six assertions is true or false and justify it.