Which of the following statements are true? [2025]
A. Unlike Ga that has a very high melting point, Cs has a very low melting point.
B. On Pauling scale, the electronegativity values of N and Cl are not the same.
C. and are all isoelectronic species.
D. The correct order of the first ionization enthalpies of Na, Mg, Al and Si is Si > Al > Mg > Na.
E. The atomic radius of Cs is greater than that of Li and Rb.
Choose the correct answer from the options given below:
C and D only
A, C and E only
A, B and E only
C and E only
(4)
A. Ga has melting point of 303 K whereas Cs has melting point of 302 K.
B. On Pauling scale, the electronegativity values of N and Cl are same i.e., 3.0.
C. All the given species are isoelectronic as all have same number of electrons (i.e., 18).
D.The correct order of first ionisation enthalpies is
E. As atomic radius increases on going down the group, hence the given statement is correct.
The correct decreasing order of atomic radii (pm) of Li, Be, B and C is [2024]
Be > Li > B > C
Li > Be > B > C
C > B > Be > Li
Li > C > Be > B
(2)
| Element | Li | Be | B | C |
| Atomic radius (pm) | 152 | 111 | 88 | 77 |
Arrange the following elements in increasing order of electronegativity: N, O, F, C, Si
Choose the correct answer from the options given below: [2024]
Si < C < N < O < F
Si < C < O < N < F
O < F < N < C < Si
F < O < N < C < Si
(1)
The electronegativity value of elements increases along a period from left to right and decreases down a group. This is because as we move along the period from left to right, nuclear charge increases and atomic radius decreases whereas, when we move down the group atomic radius as well as screening effect increases. Thus the order of electronegativity is: Si < C < N < O < F
Arrange the following elements in increasing order of first ionisation enthalpy: Li, Be, B, C, N
Choose the correct answer from the options given below: [2024]
Li < Be < B < C < N
Li < B < Be < C < N
Li < Be < C < B < N
Li < Be < N < B < C
(2)
Ionisation enthalpy increases left to right in a period but Be () has higher I.E. than B due to fully filled orbitals. Hence, the correct order is
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). [2023]
Assertion (A): Lithium and beryllium unlike their other respective group members form compounds with pronounced ionic character.
Reason (R): Lithium and Magnesium have similar properties due to diagonal relationship.
In the light of the above statements, choose the correct answer from the options given below:
(A) is true but (R) is false.
(A) is false but (R) is true.
Both (A) and (R) are true and (R) is the correct explanation of (A).
Both (A) and (R) are true but (R) is not the correct explanation of (A).
(2)
Li and Be forms predominantly covalent compounds due to small size and high charge density. The similarity in properties between lithium and magnesium arises due to diagonal relationship.
Which one of the following represents all isoelectronic species? [2023]
(4)
Total number of electrons are same in all the species as follows:
The element expected to form largest ion to achieve the nearest noble gas configuration is [2023]
N
Na
O
F
(1)
and have 10 electrons each, hence these are isoelectronic. For isoelectronic species, the size of the species decreases as the nuclear charge increases. Hence, the size decreases as
Hence, among the given elements, nitrogen is expected to form the largest ion to achieve the nearest noble gas configuration.
For the second period elements the correct increasing order of first ionization enthalpy is [2019]
Li < Be < B < C < O < N < F < Ne
Li < Be < B < C < N < O < F < Ne
Li < B < Be < C < O < N < F < Ne
Li < B < Be < C < N < O < F < Ne
(3)
As we move across a period, ionisation enthalpy increases, because of increased nuclear charge and decrease in atomic radii. However, abnormal values are observed for Be, N and Ne due to extra stability of half filled and fully filled orbitals. Thus, the actual order is,
Li < B < Be < C < O < N < F < Ne.
Match the oxide given in column I with its property given in column II. [2019]
Column I Column II
(i) A. Neutral
(ii) B. Basic
(iii) C. Acidic
(iv) D. Amphoteric
Which of the following options has all correct pairs?
(i)-B, (ii)-A, (iii)-D, (iv)-C
(i)-C, (ii)-B, (iii)-A, (iv)-D
(i)-A, (ii)-D, (iii)-B, (iv)-C
(i)-B, (ii)-D, (iii)-A, (iv)-C
(4)
-- Basic oxide, -- Amphoteric oxide,
-- Neutral oxide, -- Acidic oxide.
Which of the following oxides is most acidic in nature? [2018]
MgO
BeO
BaO
CaO
(2)
In metals, on moving down the group, metallic character increases, so basic nature increases hence most acidic will be BeO.
