Advertisements
Advertisements
प्रश्न
The order of decreasing ionisation enthalpy in alkali metals is ______.
विकल्प
Na > Li > K > Rb
Rb < Na < K < Li
Li > Na > K > Rb
K < Li < Na < Rb
Advertisements
उत्तर
The order of decreasing ionisation enthalpy in alkali metals is Li > Na > K > Rb.
Explanation:
On moving down the group as the size increases, the nuclear charge attraction decreases. The effect of increasing size outweighs the increasing nuclear charge. Thus, ionization enthalpy decreases. The order of decreasing ionization enthalpy is Li > Na > K > Rb
APPEARS IN
संबंधित प्रश्न
What are the common chemical features of alkali metals?
Why are alkali metals not found in nature?
Why are potassium and cesium, rather than lithium used in photoelectric cells?
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?
Alkali metals react with water vigorously to form hydroxides and dihydrogen. Which of the following alkali metals reacts with water least vigorously?
Which of the following elements does not form hydride by direct heating with dihydrogen?
Which of the following compounds are readily soluble in water?
(i) BeSO4
(ii) MgSO4
(iii) BaSO4
(iv) SrSO4
Choose the correct statements from the following.
(i) Beryllium is not readily attacked by acids because of the presence of an oxide film on the surface of the metal.
(ii) Beryllium sulphate is readily soluble in water as the greater hydration enthalpy of Be2+ overcomes the lattice enthalpy factor.
(iii) Beryllium exhibits coordination number more than four.
(iv) Beryllium oxide is purely acidic in nature.
Write Lewis strucure of \[\ce{O^{-}2}\] ion and find out oxidation state of each oxygen atom? What is the average oxidation state of oxygen in this ion?
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.
The metal mainly used in devising photoelectric cells is ______.
The correct order of hydration enthapies of alkali metal ions is ______.
Given below are two statements, one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : Lithium salts are hydrated.
Reason (R) : Lithium has higher polarising power than other alkali metal group members.
In the light of the above statements, choose the most appropriate answer from the options given below :
KO2 (potassium super oxide) is used in oxygen cylinders in space and submarines because it ______.
