Question

Do you observe anything happening around the zinc granules ?
Is there any change in its temperature ?
Why is glass tube not dipped in dil $H_{2}S{O}_4$ ?
How is $H_2$ gas collected by downward displacement or upward displacement of water ?
Is $H_2$ gas soluble or insoluble in water ?
Is $H_2$ gas heavier or lighter than air ?

Answer 1

$Zn+H_2{SO}_4⟶{ZnSO}_4+H_2\uparrow$

$(\ast )$ We can observe bubbles of $H_2$ gas being formed around zinc granules.

$(\ast )$ This is an exothermic reaction, i.e. it involves release heat and the flask become hot and temperature of the system increases.

$(\ast )$ The glass tube is not dipped in the solution so as to collect enough, $H_2$ gas. It is was dipped in $H_2{SO}_4$ solution would enter the tube presenting $H_2$ gas to enter the tube.

$(\ast )$ $H_2$ gas is collected by downward displacement of water.

$(\ast )$ $H_2$ gas is insoluble in water.

$(\ast )$ $H_2$ gas is lighter than air.