(a) Because the reactants are manganese dioxide and concentrated hydrochloric acid, they cannot be mixed before the reaction. Concentrated hydrochloric acid is packed in a separatory funnel, which requires a third device. The reaction condition is heating, which requires a second device, and chlorine gas is also led out by a conduit, so it is used.

So the answer is: 325;

(2) The long conduit in the fourth part introduces the generated chlorine gas into the first device, so it is necessary to connect the long conduit and the short conduit with a rubber tube, so the serial number of the instrument and conduit through which the gas flows is 25664 ①;

So the answer is: 256641;

(3) Because oxygen is produced in the bottle, the pressure in the bottle will increase, which is easy to make the rubber plug bulge or explode. Nine holes are used to make the pressure inside and outside the bottle equal;

So the answer is: make the pressure inside and outside the bottle equal;

(4) prepare a 0mol? 500 ml L-4OH solution and 500 ml volumetric flask, glass rod and rubber dropper are also needed. When the volume is constant, there is less water when looking down at the water, and the volume of the solution is too small. From 0=4V, the concentration is too high.

So the answer is: 500mL volumetric flask, glass rod, rubber-tipped dropper; High;

(9) Hypochlorite ion has strong oxidizing property and hydrogen peroxide has reducing property, so hypochlorite ion and hydrogen peroxide have redox reaction to generate chloride ion, oxygen and water, so ionic equation is 0LO-+H2O2 = 0L-+O2 = H2O, so the answer is 0LO-+H2O2 = 0L-+O2 = H2O.