Help me to answer the questions.?

Question

take a equal quantities of dilute hydrochloric acid in four test tubes.put clean piece of metals like zinc, magnesium, copper and iron respectively in each test tube. observe and record the changes.

1- frfromhich test tube do the maximum bubbles evolve?

2- which one dodoesn'troduce any bubble?

3- can you arrange the metals in the decreasing order of their speed of chemical reaction?

4- is not the nature of each metal different?

Answer 1

[1] Left for long enough Zn, Mg and Fe will produce the same amount of hydrogen (the quantity of acid being the same in each case) and so the same total number of 'bubbles' should be the same.  (Though it's better to collect the gas and measure its volume.)

However, the magnesium will produce most bubbles PER UNIT TIME, because it is the most reactive of the metals.

[2] Copper will not react with hydrochloric acid, so will not produce any bubbles.

[3] Assuming the physical state of each piece of metal is the same then, yes, you can arrange them in their order in the Reactivity Series.

[4] To make it a 'fair test' the pieces of metal need to be identical in shape and form. i.e. you can't compare iron powder and a large lump of zinc fairly.