Question

3.90 gram of a mixture of Al and Al2O3, when reacted with a
solution of NaOH produced 840 ml of gas at STP. Find composition
of mixture.

Answer 1

Answer:

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Correct option is

A

17

The reactions that are involved are:

2Al(s)+2NaOH+6H2O→2Na++2[Al(OH)4]−+3H2(g)

2 moles                                                                                      3 moles gas

Al2O3+2NaOH+3H2O→2Na++2[Al(OH)4]−

So, mass of Al in the sample =3×22400(2×27×840)=0.675 g

So, % of Al =0.675×3.9100=17.3

Therefore. the nearest integer value is 17.