Difficult Chemistry Questions. Can you answer them?

Question

1)when bubbled through calcium hydroxide solution, which will produce a white precipitate? hydrogen gas, carbon dioxide gas, ammonia gas, chlorine gas, oxygen gas.

2) which of the following substances would not form a colored solution in water? vanadium(III) chloride, zinc nitrate, iodine

3) which of the following would not have an exothermic heat of solution? potassium nitrate, nitric acid, calcium oxide

4) when added to chloroform, which would result in a purple solution? iodine, potassium permangonate, sodium chromate, mercury metal, lead(II) oxide

5) which is insoluble in both water and sulfuric acid? magnesium hydroxide, copper(II) sulfate, lead(II) nitrate, calcium chloride, mercury(II) sulfate

6) which has the highest melting point? silicon dioxide, oxygen, mercury, carbon tetrachloride, nickel(II) chloride

7) In a reaction with iron (II) sulfate, which would get oxidized? chlorine, choride, sulfur, aluminum, sulfide

Answer them if you can...

Answer 1

1) CO2

2) Zn(NO3)2

3) KNO3

4) Iodine

5) HgSO4

6) SiO2

7) Aluminum

Answer 2

From the gas law, P*V = n*R*T. n, the no of moles of the gas is M/mm, where M is the mass and mm the molecular mass (=30 for C2H6). Then P*V = (M/mm)*R*T The density is D = M/V: D = M/V = P*mm/(R*T) use R = 62.36 L*torr/(ºK*mole), P = 861 torr, T = 367ºK, to get D in gm/L. Then divide by 1000 to get gm/cm^3