| 171. | Which of the following metals is most abundant in the earth’s crust |
A. aluminium | |
B. Iron | |
C. magnesium | |
D. sodium |
| 172. | Although aluminum is more abundant than iron in the earth’s crust, why is aluminum more expensive than iron? |
A. It is more used than iron | |
B. It forms more alloys than iron | |
C. The demand for tools made from this is more than that of iron tools. | |
D. The metallurgical methods of its production are more expensive than iron. |
| 173. | Aluminum is obtained by electrolysis of pure aluminum oxide dissolved in |
A. bauxite | |
B. cryolite | |
C. feldspar | |
D. alumina |
| 174. | Which statement is not true regarding aluminum |
A. It is amphoteric in nature | |
B. It lives in free state in nature | |
C. Nitric acid has no effect on aluminum | |
D. Hot concentrated sulfur dioxide gives sulfur dioxide with aluminum. |
| 175. | Which metal is protected by its oxide |
A. Iron | |
B. Silver | |
C. Sleep | |
D. aluminium |
| 176. | Which metal is used to make airplanes and rockets? |
A. lead | |
B. aluminum | |
C. Out | |
D. Copper |
| 177. | Common alum is – |
A. K₂SO₄-AL₂(SO₄)₃-24H₂O | |
B. K₂SO₄-AI₂(SO₄)₃-21H₂O | |
C. K₂SO₄-AI₂(SO₄)₃-18H₂O | |
D. K₂SO₄-Fe₂(SO₄)₃-24H₂O |
| 178. | The chemical name of bauxite is |
A. aluminum oxide | |
B. aluminum chloride | |
C. aluminum sulfate | |
D. hydrated alumina |
| 179. | Potash alum is useful in the purification of water because it |
A. kills microbes | |
B. removes hardness of water | |
C. It precipitates colloidal solution | |
D. keeps water soft |
| 180. | Cryolite is added to the electrolysis of alumina because |
A. to increase electrical conductivity | |
B. To lower the melting point of alumina | |
C. To reduce anode effect | |
D. To separate the impurities of alumina |