State given reasons, in what state or medium does
i] NACl
ii] HCI gas
iii] `NH_(3)` gas conduct electricity .

Explain the following: (a) Sodium chloride is an ionic compound which does not conduct electricity in solid state whereas it does conduct electricity in molten state as well as in aqueous solution. (b) Reactivity of aluminium decrease if it is dipped in nitric acid. (c) Metals like calcium and magnesium are never found in their free state in nature.

Give one use with reason of I ] an aqueous solution of NH_(3) ii] liquefied NH_(3) .

Identify the following substance : A gas which does not conduct electricity in the liquid state but conducts electricity when dissolved in water.

Give reasons for the following : NH_(3) gas a covalent compound does not conduct electricity but its aq.soln. NH_(4)OH is a weak electrolyte.

Give reason for each of the following: Hydrogen chloride gas dissolves in toluene, but this solution does not conduct electricity.

Aqueous solutions of substances involving polar covalent bonds such as HCI, NH_3 and CH_3 COOH conduct electricity. Give reason.

Sodium chloride has a crystalline structure made up of Na^(+) and Cl^(-) ions. Why does NaCl not conduct electricity in solid state ?

Fill in the blanks from the choices given in brackets: The polar covalent compound in gaseous state that does not conduct electricity is …………...(carbon tetra chloride, ammonia, methane)

State what the fountain experiment demonstrates with reference to HCl gas.

In the given figure, an ideal gas changes it state from A to state C by two paths ABC and AC . (i) Find the path along which work done is the least. (ii) The internal energy of the gas at A to 10J and the amount of heat supplied to change its state to C through the path AC is 200J . Calculate the internal energy at C . (iii) The internal energy of the gas at state B is 30J . Find the amount of heat supplied to the gas to go from A to B .