1. Some metals like 147alkalicalciumchemicalcolourlessdangerousexothermicglassesgreenheathydrogenhydroxideignitesmetalnewpotassiumpurplescreensodiumtesttube react with cold water to form an 147alkalicalciumchemicalcolourlessdangerousexothermicglassesgreenheathydrogenhydroxideignitesmetalnewpotassiumpurplescreensodiumtesttube and a 147alkalicalciumchemicalcolourlessdangerousexothermicglassesgreenheathydrogenhydroxideignitesmetalnewpotassiumpurplescreensodiumtesttube gas.

2. If the gas is collected in an inverted (upside down!) 147alkalicalciumchemicalcolourlessdangerousexothermicglassesgreenheathydrogenhydroxideignitesmetalnewpotassiumpurplescreensodiumtesttube 147alkalicalciumchemicalcolourlessdangerousexothermicglassesgreenheathydrogenhydroxideignitesmetalnewpotassiumpurplescreensodiumtesttube of water (tricky!) and a lit splint applied it pops! showing the gas to be 147alkalicalciumchemicalcolourlessdangerousexothermicglassesgreenheathydrogenhydroxideignitesmetalnewpotassiumpurplescreensodiumtesttube.

3. If universal indicator is added to the water, during the reaction it changes from 147alkalicalciumchemicalcolourlessdangerousexothermicglassesgreenheathydrogenhydroxideignitesmetalnewpotassiumpurplescreensodiumtesttube (pH 147alkalicalciumchemicalcolourlessdangerousexothermicglassesgreenheathydrogenhydroxideignitesmetalnewpotassiumpurplescreensodiumtesttube) to 147alkalicalciumchemicalcolourlessdangerousexothermicglassesgreenheathydrogenhydroxideignitesmetalnewpotassiumpurplescreensodiumtesttube (pH 147alkalicalciumchemicalcolourlessdangerousexothermicglassesgreenheathydrogenhydroxideignitesmetalnewpotassiumpurplescreensodiumtesttube), showing an alkaline solution is formed.

4. This reaction is 147alkalicalciumchemicalcolourlessdangerousexothermicglassesgreenheathydrogenhydroxideignitesmetalnewpotassiumpurplescreensodiumtesttube, it should be done behind a safety 147alkalicalciumchemicalcolourlessdangerousexothermicglassesgreenheathydrogenhydroxideignitesmetalnewpotassiumpurplescreensodiumtesttube and safety 147alkalicalciumchemicalcolourlessdangerousexothermicglassesgreenheathydrogenhydroxideignitesmetalnewpotassiumpurplescreensodiumtesttube should be worn.

5. You can tell a 147alkalicalciumchemicalcolourlessdangerousexothermicglassesgreenheathydrogenhydroxideignitesmetalnewpotassiumpurplescreensodiumtesttube change is taking place because 147alkalicalciumchemicalcolourlessdangerousexothermicglassesgreenheathydrogenhydroxideignitesmetalnewpotassiumpurplescreensodiumtesttube is given out and bubbles are seen as 147alkalicalciumchemicalcolourlessdangerousexothermicglassesgreenheathydrogenhydroxideignitesmetalnewpotassiumpurplescreensodiumtesttube substances are formed.

6. The reaction of potassium with water is so 147alkalicalciumchemicalcolourlessdangerousexothermicglassesgreenheathydrogenhydroxideignitesmetalnewpotassiumpurplescreensodiumtesttube, that the heat given out 147alkalicalciumchemicalcolourlessdangerousexothermicglassesgreenheathydrogenhydroxideignitesmetalnewpotassiumpurplescreensodiumtesttube the hydrogen gas and lilac flame is seen.

7. The general equation for the reaction is:
(a) metal + cold water ==> 147alkalicalciumchemicalcolourlessdangerousexothermicglassesgreenheathydrogenhydroxideignitesmetalnewpotassiumpurplescreensodiumtesttube hydroxide + hydrogen

so complete the following ...
(b) 147alkalicalciumchemicalcolourlessdangerousexothermicglassesgreenheathydrogenhydroxideignitesmetalnewpotassiumpurplescreensodiumtesttube + water ==> potassium hydroxide + hydrogen
(c) calcium + water ==> 147alkalicalciumchemicalcolourlessdangerousexothermicglassesgreenheathydrogenhydroxideignitesmetalnewpotassiumpurplescreensodiumtesttube 147alkalicalciumchemicalcolourlessdangerousexothermicglassesgreenheathydrogenhydroxideignitesmetalnewpotassiumpurplescreensodiumtesttube + 147alkalicalciumchemicalcolourlessdangerousexothermicglassesgreenheathydrogenhydroxideignitesmetalnewpotassiumpurplescreensodiumtesttube