Alkali metals, though white, impart characteristic color to the flame because of
1. | excitation and coming back of valence electrons to the original level. |
2. | oxidation of metal in the presence of flame. |
3. | excitation of valence electrons. |
4. | gain of electrons. |
LiF is sparingly soluble in water because it has:
1. partial covalent character.
2. small electronegativity.
3. high lattice enthalpy.
4. low hydration enthalpy.
List-I | List-II | ||
(a) | Li | (i) | absorbent for carbon dioxide |
(b) | Na | (ii) | electrochemical cells |
(c) | KOH | (iii) | coolant in fast breeder reactors |
(d) | Cs | (iv) | photoelectric cell |
(a) | (b) | (c) | (d) | |
1. | (ii) | (iii) | (i) | (iv) |
2. | (iv) | (i) | (iii) | (ii) |
3. | (iii) | (iv) | (ii) | (i) |
4. | (i) | (iii) | (iv) | (ii) |
Assertion (A): | Metallic sodium dissolves in liquid ammonia giving a deep blue solution, which is paramagnetic. |
Reason (R): | The deep blue solution is due to the formation of amide. |
1. | (A) is false but (R) is true. |
2. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
3. | Both (A) and (R) are true and R is NOT the correct explanation of (A). |
4. | (A) is true but (R) is false. |
1. | Mg plays role in neuromuscular function and interneuronal transmission. |
2. | The daily requirement of Mg and Ca in the human body is estimated to be 0.2-0.3 g. |
3. | All enzymes that utilize ATP in phosphate transfer require Ca as the cofactor. |
4. | The bone in the human body is an inert and unchanging substance. |
Assertion (A): | Lithium and beryllium unlike their other respective group members form compounds with pronounced ionic character |
Reason (R): | Lithium and Magnesium have similar properties due to a diagonal relationship |
1. | (A)is true but (R) is false |
2. | (A) is false but (R) is true |
3. | Both (A) and (R) are true and (R) is the correct explanation of (A) |
4. | Both (A) and (R) are true but (R) is not the correct explanation of (A) |
I: | Hydrated chlorides and bromides of Ca, Sr and Ba on heating undergo hydrolysis. |
II: | Hydrated chlorides and bromides of Be and Mg on heating dehydration. |
The structures of beryllium chloride in solid-state, and vapor state are :
1. Dimer, and Linear, respectively.
2. Chain in both.
3. Chain, and dimer, respectively.
4. Linear in both.
Among the following alkaline earth metal halides, the one which is covalent and soluble in organic solvents is:
1. Magnesium chloride
2. Beryllium chloride
3. Calcium chloride
4. Strontium chloride