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Q1. Law of Octaves was proposed by:

• Lothar Meyer
• D.I Mendeleev
• John Alexander Newlands
• JW Dobereiner

Solution

Law of Octaves was proposed by John Alexander Newlands.

Q2. What happens to atomic radius on going from left to right in a period in a periodic table?

• Decreases
• Increases
• Remains constant
• Decreases first and then remains constant

Solution

  Atomic radius decreases with increase in atomic number on going from left to right in a period.

Q3. Inert gases belong to which block of the periodic table?

• s-block
• p-block
• d-block
• f-block

Solution

The outermost electronic configuration of inert gases is ns²np⁶.

Q4. Among the following oxides, neutral oxide is:

• CO
• SnO₂
• ZnO₂
• SiO₂

Solution

Oxides of elements placed in the centre of perodic table are amphoteric or neutral (e.g. CO, NO, N₂O).SiO₂ is slightly acidic.

Q5. Which of the following pairs have both the members from the same group of periodic table?

• Mg, Be
• Mg, Na
• Mg, Cu
• Mg, Cl

Solution

General outermost electronic configuration for both Mg and Be is ns². These are alkaline earth metals.

Q6. If x denoted the number of valence electrons of a representative element then its valence is equal to:

• x-8
• x
• 8-x
• Both option 2 and option 3

Solution

Valence of representative element is usually equal to the number of valence electrons and/or equal to eight minus the number of valence electrons.

Q7. The first period has how many orbitals?

• 4
• 3
• 2
• 1

Solution

  The first period has two orbitals and hence accommodates 2 electrons in it. Thus it justifies the fact that there are two elements in first period.

Q8. Amongst the elements of group 17, fluorine is most reactive owing to it's:

• High Electro negativity
• Small size of the atom
• Low dissociation enthalpy of F-F bond
• All of the above

Solution

Fluorine is most reactive element of group 17 due to its small size, electro negativity, extremely high oxidizing power and low dissociation enthalpy of F-F bond.

Q9. Which of the following is isoelectronic with F^-?

• Ne
• Ar
• Mg⁺
• Cl^-

Solution

Isoelectronic species have the same number of electrons.

Q10. Electrons in an orbital are filled according to which rule?

• n+n
• L+m
• n + l
• m+l

Solution

 Lowest energy orbitals are filled first and then higher energy orbital. Hence electrons in an orbital are filled according to n+l rule.

Q11. Electron gain enthalpy is most negative for:

• Phosphorus
• Sulphur
• Chlorine
• Fluorine

Solution

Electron gain enthalpy generally becomes more negative across a period from left to right. In the group, electron gain enthalpy becomes less negative down a group. However, adding an electron to 2p orbital leads to greater repulsion than adding an electron to the larger 3p orbital. Thus, the element with most negative electron gain enthalpy is chlorine and the one with least electron gain enthalpy is phosphorous.

Q12. How many valence electrons does a carbon atom have?

• 6
• 4
• 3
• 2

Solution

The electrons present in the outermost shell are called valence electrons.

Q13. The maximum number of elements present in seventh period of the modern periodic table is:

• 18
• 8
• 32
• 2

Solution

The total number of electrons that can be accommodated in seventh period are 2(in 7s) + 14(in 5f) + 10(in 6d )+ 6(in 7p) = 32. The maximum number of elements present in it is 32.

Q14. Which scientist proposed that atomic number is more fundamental property of an element than its atomic mass?

• Meyer
• Moseley
• Lothar Meyer
• Newlands

Solution

Moseley performed experiments and studied the frequencies of the rays emitted from the elements. With these experiments he concluded that atomic number is more fundamental property of an element than its atomic mass.

Q15. In Na₂O oxidation state of oxygen is:

• +2
• +1
• -1
• 0

Solution

In Na₂O oxidation state of Na is +1.

Q16. Alkaline earth metals include:

• Group 1 element
• Group 2 elements
• Group 18 elements
• Group 17 elements

Solution

Group 2 elements are known as alkaline earth metals because their oxides are alkaline in nature and these oxides remain unaffected by heat or fire and existed in earth.

Q17. Which of the following elements belongs to the same group as the element having configuration 1s² 2s² 2p¹

• B: (1s² 2s² 2p⁶ 3s² 3p¹)
• C: (1s² 2s² 2p⁶ 3s² 3p³)
• D: (1s² 2s² 2p⁶ 3s² 3p⁵)
• E: (1s² 2s² 2p⁶ 3s² 3p⁶ 4s²)

Solution

The electronic configuration of B is 1s² 2s² 2p⁶ 3s² 3p¹ and the number of electron in last p orbital is 1 so it belongs to the same group as element with configuration (1s² 2s² 2p¹).

Q18. Which element acts as strong reducing agent?

• Those elements that can share electron
• he elements which readily lose electron
• The elements which readily gain electron
• None of above

Solution

The elements which readily lose electron act as strong reducing agent.

Q19. The p-block elements constitute elements belonging to which groups?

• Group 1 to 18
• Group 10 to 14
• Group 1 to 13
• Group 13 to 18

Solution

  The p-block elements constitute elements belonging to group 13 to 18 and these together with the s-Block elements are called Representative elements.

Q20. How many orbitals are filled in second period?

• 3
• 1
• 4
• 6

Solution

  The 4 orbitals filled in second period are one 2s (with 2 electrons) and three 2p (with 6 electrons). 

Q21. The nature of bonds in the compounds of carbon is mostly:

• Covalent
• Electrovalent
• Covalent as well as electrovalent
• Metallic

Solution

Carbon froms covalent compounds because the sum of first four ionization enthallpies is very high.

Q22. The oxygen family is also known as:

• chalcogen family
• oxo family
• halogen family
• peroxo family

Solution

The oxygen family (Group 16) is also known as the chalcogen family.

Q23. What is the relationship between the number of elements in each period and the number of atomic orbitals available in the energy level that is being filled?

• Number of elements is twice the number of atomic orbitals.
• Number of elements is same as the number of atomic orbitals.
• Number of elements is three times the number of atomic orbitals.
• Number of elements is half the number of atomic orbitals.

Solution

Number of elements is twice the number of atomic orbitals. 

Q24. The element with lowest ionization energy among the following is:

• Li
• Na
• K
• Rb

Solution

The ionization energies of alkali metals decrease progressively as we move down the group due to addition of new shells. Since Rb is at bottom position among the given elements hence, it has the lowest ionization energy among the given elements.

Q25. The systemic name for an element with atomic number (Z = 118) is:

• Unnilunium
• Ununhexium
• Ununoctium
• Unbinilium

Solution

The systematic name for an element with atomic number (Z = 118) is ununoctium.

Q26. The correct general outer electronic configuration of group 13 elements is:

• ns² np¹
• ns² np³
• ns² nd¹
• ns² np⁶

Solution

The correct general electronic configuration of group 13 elements is ns² np¹ since they have 3 electrons in valence shell.

Q27. The Latin word commonly used for the digit 9 is:

• Nil
• Quad
• Hex
• Enn

Solution

The Latin word commonly used for the digit 9 is "enn". It is abbreviated as "e".

Q28. Identify the element belonging to third period and 17^th group of the periodic table.

• Chlorine
• Bromine
• Sulphur
• Silicon

Solution

Chlorine belongs to third period and 17^th group of the periodic table. Its atomic number is 17 and its configuration is 2, 8, 7.

Q29. Identify the smallest ion among the following:

• Na⁺
• Mg²⁺
• K⁺
• Al³⁺

Solution

More the nuclear charge on ion, electrons  are more strongly attracted and thus size decreases. Hence, among the given ions Al³⁺ is the smallest ion.

Q30. The maximum covalence of the first member of each group is:

• 2
• 4
• 6
• 8

Solution

The first member of group has only four valence orbitals (2s and 2p for bonding). So the maximum covalence of the first member of each group is 4.

Q31. Elements of Group-1 are called:

• Alkaline earth metals
• Chalcogens
• Alkali metals
• Halogens

Solution

  The elements of Group-1 are called alkali metals and have the outer electronic configuration of ns¹.

Q32. What is the maximum number of electrons that can be filled in 3d subshell?

• 2
• 6
• 10
• 14

Solution

There are 5 orbitals in d subshell  and each orbital can accommodate 2 electrons. Hence maximum number of electrons that can be filled in 3d subshell is 10.

Q33. The valence of sodium with atomic number 11 is:

• 4
• 2
• 3
• 1

Solution

  Valence of Na  = 1 since its electronic configuration is 1s² 2s² 2p⁶ 3s¹

Q34. Eka silicon predicted by Mendeleev is which element:

• Germanium
• Sodium
• Gallium
• Aluminium

Solution

  Eka silicon predicted by Mendeleev is Germanium.

Q35. Lothar Meyer proposed that on arranging the elements in order of increasing atomic weights; similarities appear in which type of properties?

• In both physical and chemical properties
• Only physical properties
• Only chemical properties
• thermodynamic properties

Solution

Lothar Meyer proposed that on arranging the elements in order of increasing atomic weights similarities appear in both physical and chemical properties.

Q36. The longest period are sixth and seventh periods.

• sixth and seventh periods.
• sixth and seventh periods.
• sixth and seventh periods.
• sixth and seventh periods.

Solution

The longest period are sixth and seventh periods. They both contain 32 elements respectively.

Q37. The basis of long form of periodic table is:

• Atomic weight
• Mass number
• Atomic number
• Ionic radius

Solution

In long form of periodic table elements are arranged in increasing order of their Atomic number.

Q38. The element which shows only negative oxidation state/s among following elements is:

• Chlorine
• Bromine
• Iodine
• Fluorine

Solution

Fluorine has highest electronegativity among all known elements, so it shows only negative oxidation states.

Q39. Modern periodic table is divided into:

• 18 periods and 7 groups
• 7 periods and 18 groups
• 8 periods and 18 groups
• 18 periods and 8 groups

Solution

Modern periodic table is divided into 7 periods and 18 groups.

Q40. Johann Dobereiner classified elements in group of three elements called as

• Diads
• Triads
• Trinity
• Trials