How will you prepare hydrogen in laboratory?

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Dihydrogen gas is prepared in the laboratory by the action of dilute sulphuric acid on granulated zinc in a Woulfe’s bottle.




Dilute sulphuric acid is poured dropwise through thistle funnel on granulated zinc pieces, hydrogen gas is produced which is collected by the downward displacement of water.
Sometimes, the bubbles of hydrogen formed to adhere to the surface of zinc metal and this prevents the further attack of acid on the metal.
To check this, a small amount of copper sulphate is added along with granulated zinc.