Amorphous boron of `95%` to `98%` purity is obtained by:A. heating `B_(2)O_(3)` with `H_(2)`B. heating `B_(2)O_(3)` with `Mg` or `Na` at high temperature.C. heating `KBF_(4)` with `Na` or `K`.D. heating `BBr_(3)` with `H_(2)` in presence of a catalyst.

Amorphous boron of `95%` to `98%` purity is obtained by:A. heating `B_

1.	Amorphous boron of `95%` to `98%` purity is obtained by:A. heating `B_(2)O_(3)` with `H_(2)`B. heating `B_(2)O_(3)` with `Mg` or `Na` at high temperature.C. heating `KBF_(4)` with `Na` or `K`.D. heating `BBr_(3)` with `H_(2)` in presence of a catalyst.
Answer» Correct Answer - B `B_(2)O_(3)+3Mg` or `Naunderset(Delta)overset("High temperature")to2B+3MgO //Na_(2)O`

vii. The stability of dihalides of ` Si, Ge , Sn` and Pb increases steadily in the sequence :A. `GeX_(2) lt SiX_(2) lt SnX_(2) lt PbX_(2)`B. `SiX_(2) lt GeX_(2) lt PbX_(2) lt SnX_(2)`C. `SiX_(2) lt GeX_(2) lt SnX_(2) lt PbX_(2)`D. `PbX_(2) lt SnX_(2) lt GeX_(2) lt SiX_(2)`
When `H_2S` is passed through acidified `KMNO_4`, we getA. `K_(2)SO_(4)`B. `MnO_(2)`C. `KHSO_(3)`D. Sulphur
The`3ClO^(-)(aq.)to ClO_(3)^(-)(aq.)+2Cl^(-)(aq.)` is an example ofA. oxidation reactionB. disproportionationC. reduction reactionD. decomposition
The reaction: `ClO_(3)^(-) +I_(2) to IO_(3)^(-)+Cl_(2)`A. is possibleB. depends upon the state of productsC. is not possibleD. depends upon the temperature
In the reaction: `3Br_(2)+6OH^(Theta)rarr 5Br^(Theta)+BrO_(3)^(Theta)+3H_(2)O,Br_(2)` isA. is reducedB. is oxidizedC. disproportionatesD. disintegrate
`NaClO_(3)` is obtained by reacting `Cl_(2)` andA. cold dil. NaOHB. hot conc. NaOHC. cold `Na_(2)O_(2)`D. hot `Na_(2)O_(2)`
Which of the following is acidic oxides ?A. `HClSO_(4)`B. `MgO`C. `Al_(2)O_(3)`D. `CaO`
Which of the following is more acidic oxyacid ?A. `HClO_(4)`B. `HClO`C. `HClO_(3)`D. `HClO_(2)`
Oxygen orm acidic oxide withA. CaB. NaC. SD. K
Of the following, the most acidic isA. `As_(2)O_(3)`B. `P_(2)O_(3)`C. `Sb_(2)O_(3)`D. `Bl_(2)O_(3)`