10

Q1. Li and Mg both form chlorides which are:

• Deliquescent
• Highly ionic
• Unstable
• Alkaline

Solution

Both LiCl and MgCl₂ are deliquescent as they readily dissolve in water which they absorb.

Q2. Alkali metals are characterized by:

• Good conductor of heat and electricity
• High melting points
• Low oxidation potential
• High ionization potentials

Solution

Alkali metals are characterized by good conductor of heat and electricity.

Q3. What is the oxidation state of  Rb in RbO₂?

• +1
• -1
• +2
• -2

Solution

The superoxide species is O₂^-, as the compound is neutral so the oxidation state of Rb is +1.

Q4. The general electronic configuration of the outermost orbit in the case of alkaline earth metal is:

• ns²
• ns²np¹
• ns²np⁴
• ns¹

Solution

Alkaline earth metal belongs to Group 2 of periodic table and has electronic configuration ns².

Q5. Alkali metals are powerful reducing agent because:

• These are metals
• These are monovalent
• Their ionic radii are large
• Their ionization potentials are low

Solution

Due to low ionization potential they can easily loose electron and thus acts as powerful reducing agent.

Q6. Why do the melting points of group 2 elements not show regular trends?

• Atoms of elements have smaller size
• Atoms adopt different crystal structures
• Atoms have large ionic radii
• Atoms have high nuclear charges

Solution

Melting points of group 2 elements show irregular trends becuase atoms adopt different crystal structures.

Q7. Beryllium carbide reacts with water to give:

• Methane
• Acetylene
• Ethane
• Propane

Solution

Beryllium carbide reacts with water to give methane.

Q8. In Castner Kellner cell:

• Hg is cathode and carbon is anode
• Hg is anode and carbon is cathode
• Hg is cathode and anode
• Carbon is anode and cathode

Solution

In Castner Kellner cell, Hg is cathode and carbon is anode.

Q9. Cs reacts with chlorine to form:

• CsCl
• Cs₂Cl₂
• CsCl₂
• CsCl₃

Solution

Alkali metals readily reacts with halogens to form ionic haides. 2Cs  +    Cl   2 CsCl

Q10. Which of the following statements is correct?

• All alkali metals form monoxides
• Li forms a monoxide and Na forms a peroxide while all others form superoxides
• Na forms a monoxide and Li forms a peroxide while all others form superoxides
• Li forms a monoxide and Na forms a superoxide while all others form peroxides

Solution

Li forms a monoxide and Na forms a peroxide while all others form superoxides due to the fact that a small cation can stabilize a small anion and the large cation can stabilize a large anion.

Q11. Which of the following is a correct statement?

• All alkali metal nitrates decompose on heating to produce NO₂
• All alkaline earth metal nitrates decompose on heating to produce NO₂
• All alkali metal nitrates decompose on heating to produce NO
• All alkali metal nitrates decompose on heating to produce NO

Solution

All alkaline earth metal nitrates decompose on heating to produce NO₂, the corresponding oxide and O₂.

Q12. Bones and teeth contains:

• Ca
• Mg
• Na
• K

Solution

99% of body calcium is present in bones and teeth.

Q13. A substance X is a compound of an element of group 1, and gives violet colour in flame test. X is:

• NaCl
• LiCl
• KCl
• CsCl

Solution

Since potassium gives violet colour on flame test, the substance X is KCl.

Q14. In the periodic table the element with atomic number 38 belongs to:

• Period IV and group II
• Period IV and group IV
• Period III and group IV
• Period V and group II

Solution

The electronic configuration of element is 1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4p⁶5s². Since the period is determined by the shell number that is 5 (in this case) and group is determined by the number of electron in outermost orbital that is 2 (in this case), hence the element belongs to Group II and period V i.e. alkaline earth metal.

Q15. In Castner Kellner cell, electrolyte used is:

• aq. NaOH
• aq. NaCl
• Na/Hg
• aq. NaBr

Solution

In Castner Kellner cell, brine i.e. aq. NaCl is electrolysed to produce NaOH.

Q16. Carbonates of alkali and alkaline earth metals differ in:

• Stability
• Lattice enthalpy
• Solubility
• All the above

Solution

Due to difference in size of cation involved, carbonates of alkali and alkaline earth metals differ in stability, lattice enthalpy and solubility.

Q17. Sodium reacts with water more vigorously than lithium because:

• It has a higher atomic weight
• It is more electropositive
• It is more electronegative
• It is a metal

Solution

This behaviour of lithium is attributed to its small size and very high hydration energy. Sodium is more electropositive than lithium.

Q18. Li shows difference in properties than rest of the members of its group but shows similarities with:

• Be
• Al
• Mg
• Ca

Solution

Due to diagonal relationship, Li resembles Mg.

Q19. The nature of the oxide of radium is:

• Acidic
• Basic
• Neutral
• Amphoteric

Solution

Since radium belongs to alkaline earth metals, its oxide is basic in nature.

Q20. As compared to Potassium, Sodium has:

• Less ionization potential
• More ionization potential
• Larger atomic radius
• Lower melting point

Solution

Ionization potential decreases as atomic size increases down the group.

Q21. Aqueous solution of which of the following compounds is used to detect carbon dioxide:

• Be(OH)₂
• Mg(OH)₂
• Sr(OH)₂
• Ca(OH)₂

Solution

Aqueous solution of Calcium hydroxide(lime water) gives a white precipitate of Calcium carbonate and carbon dioxide gas is evolved.

Q22. Beryllium hydride is a ------ compound.

• Covalent
• Ionic
• Electrovalent
• Polar

Solution

Beryllium does not combine directly with hydrogen to form hydride. Beryllium hydride is a  covalent compound.

Q23. Be can show coordination number four while other members show a value of six. This is because of:

• Small size of Be
• Non availability of d orbitals in Be
• Availability of d orbitals in Be
• High ionization enthalpy of Be

Solution

Due to non availability of d orbitals in Be, it can show coordination number four while other members show a value of six.

Q24. Strongest reducing agent among the following is:

• Li
• K
• Na
• Cs

Solution

Due to small size of Lithium ion, it has the highest hydration enthalpy which account for high negative E value.

Q25. Property of the alkaline earth metals that increases with their atomic number is:

• Ionization energy
• Solubility of their hydroxides
• Solubility of their sulphates
• Electro-negativity

Solution

The solubility of the alkaline earth metal hydroxides increases with increase in atomic number due to the decrease in lattice energy on moving down the group.

Q26. Potassium when heated strongly in oxygen forms:

• KO₂
• K₂O₂
• K₂O
• KO

Solution

Potassium forms superoxide ( KO₂) on reaction with oxygen.

Q27. Which of the following is amphoteric?

• BeO
• MgO
• CaO
• All the above

Solution

BeO is amphoteric.

Q28. When sodium is oxidized it forms:

• Oxides
• Peroxides
• Superoxides
• Hydroxides

Solution

When sodium is oxidized it forms peroxides. 2Na + O₂  Na₂O_{2 ( peroxides)}

Q29. Alkali metals are powerful reducing agent because:

• These are metals
• These are monovalent
• Their ionic radii are large
• Their ionization potentials are low

Solution

Alkali metals can easily lose electrons because of low ionization potentials.

Q30. Be is not readily attacked by acids because:

• Of formation of protective chloride layer on the surface.
• It is stable.
• It is less reactive.
• Of formation of protective oxide layer on the surface.

Solution

Be is not readily attacked by acids because of formation of protective oxide layer on the surface.

Q31. Sodium reacts with water more vigorously than lithium because:

• It has a higher atomic weight
• It is more electropositive
• It is more electronegative
• It is a metal

Solution

On moving down the group electropositive nature increases hence sodium is more electropositive than lithium.

Q32. Alkaline earth metals show:

• Divalency
• Monovalency
• Zero valency
• Variable valency

Solution

Since the outermost orbital contain only two electrons, alkaline earth metals show divalency by losing these two electrons.

Q33. Which one of the following alkaline earth metal sulphates has its hydration enthalpy greater than its lattice enthalpy?

• CaSO₄
• BeSO₄
• BaSO₄
• SrSO₄

Solution

BeSO₄ BeSO₄ has hydration enthalpy greater than lattice enthalpy.

Q34. Magnesium when heated in the atmosphere of nitrogen gives nitride. The formula of nitride is:

• MgN
• Mg₃N₂
• Mg₃N
• Mg₂N

Solution

The formula of Magnesium nitride is Mg₃N₂.

Q35. Which of the following is kept under kerosene:

• Sodium
• Lithium
• Rubidium
• Cesium

Solution

Sodium metal is very reactive.

Q36. Solubility of s block halides in water depends upon:

• Ionization energy of metal
• Lattice energy of compound
• Hydration energy of ions
• Both 2 and 3

Solution

Solubility of an ionic compound in water depends upon lattice energy of compound and hydration energy of ions.

Q37. Name the element which forms the stable fluoro complex anions:

• Be
• Ba
• Ca
• Sr

Solution

Be forms anion which is stable. This is due to small size and higher charge density.

Q38. When CaCO₃ is treated with HCl, a colourless odourless gas is evolved. The gas is:

• CaO
• CaCO₂
• CO₂
• O₂

Solution

Q39. Which of the following dissolves in ethanol?

• LiCl and MgCl₂
• NaCl and MgCl₂
• KCl and MgCl₂
• RbCl and MgCl₂

Solution

LiCl and MgCl₂ both are soluble in ethanol.

Q40. Be and Mg do not react with water. This is because of:

• High ionization enthalpy
• Formation of protective oxide layer
• High electron gain enthalpy
• High enthalpy of atomization