Roasting

Q. Which of the following hydrides cannot be obtained by direct reaction between the elements?

1. BeH₂

2. LiH

3. CaH₂

4. NaH

Q. Process of heating the ores strongly in presence of oxygen, during which sulfide is converted to an oxide is called roasting.

1. True
2. False

Q. 81 Consider the reaction, 2A(g)+B(g)=2C(g) for which k*c=350.if mole of each of the reactant and product are mixed in a 2.0L flask, then the reaction quitent and the spontaneous direction of the system will be?

Q.

Of the given options, choose the combination that contains metals whose ores are most appropriate for roasting. In other words, Sulphide ores are common for which kind of metals?

1. Ag, Cu, Pb

2. Ag, Cu, Sn

3. Ag, Mg, Pb

4. Al, Cu, Pb

Q. $A$ and $B$ are two ores of copper.
$A$ undergoes calcination to form a solid, $C{O}_{2\left(g\right)}$ and $O_{2\left(g\right)}$
$B$ undergoes roasting to form a solid and a gas $C$ which turns acidified $K_{2}C{r}_2{O}_7$ to green solution.
$B$ also reacts with dil $HCl$ to form a solid and gas $D$ which turns lead acetate solution black. $D$ also reacts with $C$ to form colloidal sulphur in the presence of moisture.

The nature of the gas ($D$) and hybridization of the central atom is respectively:

1. Weakly acidic, $s{p}^3$
2. Strongly acidic, $s{p}^3$
3. Weakly acidic, $s{p}^2$
4. Strongly acidic, $s{p}^2$