State whether the following statements are true or false with reasons.
a. Elastic forces are always conservative.
b. Elastic forces are strictly conservative only when Hooke's law is obeyed.
c. When a wire is loaded beyond the elastic limit and then reloaded, the work done disappears completely as heat.

State whether the following statements are true or false : When the electric current through the fuse exceeds a certain limit, the fuse wire melts and breaks.

State the following statements as true or false. a. The work done by a force on a body is equal to the dot product of the force and displacement of the body. b. Instantaneously, work is not defined. c. When several forces act on a body, the total work is the same as the work done by their resultant.

State if each of the following statements is true or false. Give reasons for your answer. a) In an elastic collision of two bodies, the momentum and energy of each body is conserved. b)Total energy of a systm is always conserved,no matter what internal and external forces on the body are present. Work done in the motion of a body over a closed loop is zero for every force in nature. d) In an inelastic collision, the final kinetic energy is always less than the initial kinetic energy of the sytem.

A parallel plate air capacitor is connected to a battery. If the plates of the capacitor are pulled farther apart, then state whether the following statements are true or false. a. Strength of the electric field inside the capacitor remains unchanged, if the battery is disconnected before pulling the plates. b. During the process, work is done by the external force applied to pull the plates irrespective of whether the battery is disconnected or not. c. Strain energy in the capacitor decreases if the battery remains connected. .

State whether the following statements are true or false. a. D and L stereoisomers are enantiomers. b. D enantiomer rotates the plane-polarised light to the right and L enantiomer to the left. c. Conversion of an erythro to a threo stereoisomer always occur by inversion at one chiral C . d. A racemate can be distinguished from a meso or a chiral compound by an attempted resolution. e. Racemisation of an enantiomer can only occure by breaking of at least one bond to the chiral centre. f. A reaction catalysed by an enzyme always gives an O.A product. g. When an achiral molecule reacts to give achiral molecule, the product is always racemic h. In chemical reactions, the change from an S reactant to an R product always signals an inversion of configuraion. i. An optically inactive substance must be achiral. j. An achiral compound can have chiral centres. K. A compound with S configuration is the (-) enantiomer.

State whether the following statements are true or false. (a) An electric motor converts mechanical energy into electrical energy. (b) An electric generator works on the principle of electromagnetic induction. (c) The field at the centre of a long circular coil carrying current will be parallel straight lines. (d) A wire with a green insulation is usually the live wire.