21. The solubility of alkaline earth metal hydroxides in water generally:

a) Increases down the group
b) Decreases down the group
c) Remains constant
d) Increases up the group
Answer: a) Increases down the group

22. Which of the following is the least reactive alkali metal?

a) Sodium
b) Lithium
c) Rubidium
d) Cesium
Answer: b) Lithium

23. The ionization energy of alkali metals:

a) Increases down the group
b) Decreases down the group
c) Remains constant
d) Increases across the period
Answer: b) Decreases down the group

24. The oxide of which s-block element is most basic?

a) Sodium
b) Magnesium
c) Calcium
d) Barium
Answer: d) Barium

25. Which of the following s-block elements forms a compound that is a strong base in water?

a) Lithium
b) Barium
c) Sodium
d) Potassium
Answer: b) Barium

26. The solubility of alkali metal salts in water generally:

a) Increases down the group
b) Decreases down the group
c) Remains constant
d) Increases up the group
Answer: a) Increases down the group

27. Which alkaline earth metal forms a compound used in fireworks for a red color?

a) Beryllium
b) Magnesium
c) Calcium
d) Strontium
Answer: d) Strontium

28. The s-block element that forms an amphoteric oxide is:

a) Sodium
b) Magnesium
c) Calcium
d) Potassium
Answer: b) Magnesium

29. Which of the following is a property of alkali metals?

a) High melting points
b) High density
c) Soft and can be cut with a knife
d) Low reactivity with water
Answer: c) Soft and can be cut with a knife

30. The reactivity of alkaline earth metals with water is generally:

a) Higher than alkali metals
b) Lower than alkali metals
c) Same as alkali metals
d) Non-existent
Answer: b) Lower than alkali metals