Which complex among the following gives a white precipitate on treatment with an aqueous solution of barium chloride?

When $\mathrm{CuSO}_4$ solution in water is treated with concentrated HCl it turns

Which of the following polymer is used in paints?

Three moles of an ideal gas are expanded isothermally from a volume of $300 \mathrm{~cm}^3$ to 2.5 L at 300 K against a pressure of 1.9 atm . The work done in joules is