2015 - JAMB Chemistry Past Questions and Answers - page 6

Alloy is a metal that consist of two or more metals mixed together e.g. is mass which is an alloy of copper and zinc. Are not prepared with option A,B,C, and the do not result in mixture and metals together

Salt is good chemical agent that lowers the melting of an ice only it temperature below 0°C options B,C,D will not have the melting point except is above the 0° C. only salt does that.

CH_4(g) + 2O_2(g) → 2H₂O_(g)
1 volume of methane will react with 90cm³ of oxygen at S.T.P

Oxygen is a substance that is used to remove impurities from pig iron. Options B, C, D will be effective in removing impurities positive]

Carbon concentration of 4 will not give a precipitate heating. Option B,C,D will not be dehydrated

Rare gases are stable because they have duplet or octet electronic configurations in the outermost shells in their atoms, as a result they don’t go into solution easily. option A, B, Dare not because they go into solution easily (unstable)

Ethanol has the molecular formula C2H6O. Option A, C, D are not because their molecular are not different

The bubble remain the same because entropy favors the mixture as it is the degree of randomness or disorderliness. Option B,C,D will not favors the entropy

[H+][OH−] = 10 − 4
[H+] =10 − 14 ÷ [OH+]
=10 −14 ÷ (1 × 10 − 3) = 10 − 11
pH = − log10[H+ ]
= − log10[10 − 11] = − 1 × −11
log10[10 − 11] = 1
= − 1 × 11 × 1
= − 11