During compression of a spring the work done is 10kJ and 2kJ escaped to the surroundings as heat. The change in internal energy, $$\Delta $$U(inkJ) is :

Increasing order of reactivity of the following compounds for S_N1 substitution is:

HF has highest boiling point among hydrogen halides, because it has :

In an acid-base titration, 0.1 M HCl solution was added to the NaOH solution of unknown strength. Which of the following correctly shows the change of pH of the titraction mixture in this experiment?