The soldiers of the Napolean army while at the Alps during freezing winter suffered a serious problem with regards to the tin buttons of their uniforms. White Metallic tin buttons get converted to grey powder. This transformation is related to-
1. An interaction with water vapour contained in humid air
2. A change in the crystalline structure of tin
3. A change in the partial pressure of in the air
4. An interaction with of air at low temperature
The amphoteric oxide among the following is -
1. | \(\mathrm{CO}_2 \) | 2. | \(\mathrm{PbO}_2 \) |
3. | \(\mathrm{SiO}_2 \) | 4. | \(\mathrm{SeO}_2\) |
Aluminium chloride in acidified aqueous solution forms a complex 'A'.
The formula of A and hybridisation state of Al in 'A' is respectively:
1. [Al(H2O)6]3+, sp3d2
2. [Al(H2O)4]3+, sp3
3. [Al(H2O)4]3+, dsp2
4. [Al(H2O)]3+, d2sp3
When reacts with , the product formed is-
1.
2.
3.
4. None of the above
Quartz is made of silicon and oxygen joined in a network arrangement that is similar to:
1. Diamond
2. Graphite
3.
4. None of the above
CO2 and N2 are non-supporters of combustion. However, for putting out fires CO2 is preferred over N2 because CO2:
1. Does not burn.
2. Forms non-combustible products with burning substances.
3. Is denser than nitrogen.
4. Is a more reactive gas.
When Al is added to the potassium hydroxide solution:
1. No reaction takes place
2. Oxygen gas is evolved
3. Water is produced
4. Hydrogen gas is evolved
Which among the following is a gas?
1.
2.
3.
4.
Orthoboric acid when heated to red hot gives-
1. | Metaboric acid | 2. | Pyroboric acid |
3. | Boron and water | 4. | Boric anhydride |
Boric acid on heating at gives:
1.
2.
3.
4.