Question

pls answer this question​

Answer 1

1:-

$4Al + 3 O_{2} --->2Al _{2} O_{3}</p><p> </p><p></p><p>$

(aluminium oxide)

2:-

$3Fe + 4H_{2}O --->Fe_{3}O_{4}+4H_{2}$

(ferric oxide)

3:-

$Ca + H_{2}O-->CaO+H_{2}$

(quicklime

or calicum oxide)

the calcium starts floating because the hydrogen form bubbles in water and bubble get covered on the surface of calcium.