Advertisements
Advertisements
प्रश्न
The alkali metals are low melting. Which of the following alkali metal is expected to melt if the room temperature rises to 30°C?
विकल्प
Na
K
Rb
Cs
Advertisements
उत्तर
Cs
Explanation:
Among alkali metals, melting point decreases as the strength of metallic bonding decreases with increasing size of the atom. Thus, Cs has the lowest melting point (28.5°C) and will melt at 30°C.
APPEARS IN
संबंधित प्रश्न
Explain why alkali and alkaline earth metals cannot be obtained by chemical reduction methods?
Why are potassium and cesium, rather than lithium used in photoelectric cells?
When an alkali metal dissolves in liquid ammonia the solution can acquire different colours. Explain the reasons for this type of colour change.
Write a balanced equation for the reaction between KO2 and water.
Write a balanced equation for the reaction between Na2O and CO2.
Which of the alkali metal is having least melting point?
Which one of the following alkali metals gives hydrated salts?
For alkali metals, which one of the following trends is incorrect?
Which of the following statements is incorrect?
Metals form basic hydroxides. Which of the following metal hydroxide is the least basic?
In the synthesis of sodium carbonate, the recovery of ammonia is done by treating NH4Cl with Ca(OH)2. The by-product obtained in this process is ______.
When heated in air, the alkali metals form various oxides. Mention the oxides formed by Li, Na and K.
When a metal of group 1 was dissolved in liquid ammonia, the following observations were obtained:
(i) Blue solution was obtained initially.
(ii) On concentrating the solution, blue colour changed to bronze colour.
How do you account for the blue colour of the solution? Give the name of the product formed on keeping the solution for some time.
The stability of peroxide and superoxide of alkali metals increase as we go down the group. Explain giving reason.
Match List-I with List-II.
| List-I | List-II |
| (Metal) | (Application) |
| (a) Cs | (I) High temperature thermometer |
| (b) Ga | (II) Water repellent sprays |
| (c) B | (III) Photoelectric cells |
| (d) Si | (IV) Bullet proof vest |
Choose the most appropriate answer from the options given below:
The metal mainly used in devising photoelectric cells is ______.
The correct order of conductivity of ions in water is ______.
KO2 (potassium super oxide) is used in oxygen cylinders in space and submarines because it ______.
