Question 1

Among the following options, the correct trend in the electron gain enthalpy is

Accepted Answer

The electron gain enthalpy generally becomes less negative as we move down a group due to the increase in atomic size. However, fluorine has a less negative electron gain enthalpy than chlorine. This is because fluorine has a very small atomic size, leading to strong interelectronic repulsions in the compact 2p subshell. As a result, the incoming electron experiences less attraction from the nucleus compared to chlorine. The values of electron gain enthalpy for halogens are approximately: Cl = -

Question 2

Given below are two statements : One is labelled as Assertion A and the other is labelled as Reason R . Assertion A : The first ionization enthalpy of O is lower than that of N and F. Reason R : The l

Accepted Answer

The electronic configuration of N is 1s^2 2s^2 2p^3. The electronic configuration of O is 1s^2 2s^2 2p^4. The electronic configuration of F is 1s^2 2s^2 2p^5. Generally, the first ionization enthalpy increases across a period due to an increase in effective nuclear charge. Therefore, the ionization enthalpy of F is higher than that of O . However, N has a stable half-filled 2p^3 configuration, which makes it difficult to remove an electron, resulting in a higher ionization enthalpy than O . For

Question 3

Identify the incorrect statement from the following :

Accepted Answer

Atomic radius decreases across a period from left to right, so the atomic radius of Mg is greater than that of Al . For isoelectronic species, the ionic radius decreases with an increase in nuclear charge. Both Mg ^ 2+ and Al ^ 3+ have 10 electrons, but Al ^ 3+ has a higher nuclear charge (Z=13) compared to Mg ^ 2+ (Z=12), making Al ^ 3+ smaller than Mg ^ 2+ . Cations are always smaller than their respective parent atoms. Therefore, the overall decreasing order of size is Mg > Al > Mg ^ 2+ > Al

Question 4

The correct order of increasing metallic character of Na, Be, P, Mg and Si is :

Accepted Answer

Metallic character is the tendency of an element to lose electrons. It decreases across a period from left to right and increases down a group. The elements Na , Mg , Si , and P belong to the third period. Across a period, metallic character decreases, so the order is Na > Mg > Si > P . The elements Be and Mg belong to Group 2. Down a group, metallic character increases, so Mg > Be . Comparing Be (a metal) with Si (a metalloid) and P (a non-metal), Be is more metallic than both Si and P . Combin

Question 5

Which of the following statements are true? 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

Accepted Answer

(C) Ca ^ 2+ , K ^ + , Ar , Cl ^ - , S ^ 2- all species have 18 electrons that's why these are isoelectronic species. (E) Radius order Cs Rb K Na Li

Question 6

Which among the following electronic configurations belong to main group elements? A. [ Ne ] 3 ~s ^1 B. [ Ar ] 3 ~d ^3 4 ~s ^2 C. [ Kr ] 4 d^ 10 5 s^2 5 p^5 D. [ Ar ] 3 ~d ^ 10 4 ~s ^1 E. [R n] 5 f^0

Accepted Answer

Main group elements are s & p-block elements. A s-block C p -block

Question 7

Match List-I with List-II : Identify the correct answer from the options given below:

Accepted Answer

The correct match is A-III, B-IV, C-I, D-II

Question 8

Arrange the following elements in increasing order of first ionization enthalpy: Li , Be , B , C , N Choose the correct answer from the options given below:

Accepted Answer

Increasing order of first ionization enthalpy is Li B Be C N array |c|c| Element & array l First ionization enthalpy \ ( _ i H / kJ mol ^ -1 . ) array \ Li & 520 \ Be & 899 \ B & 801 \ C & 1086 \ N & 1402 \ array

Question 9

Match List-I with List-II: Choose the correct answer from the options given below:

Accepted Answer

array lll Element & & Block/group in periodic table \ (Z=58) & & Lanthanoid \ (Z=33) & & p-block element \ (Z=55) & & s-block element \ (Z=25) & & d-block element array A-I, B-IV, C-II, D-III

Question 10

Arrange the following elements in increasing order of electronegativity: N , O , F , C , Si Choose the correct answer from the options given below:

Accepted Answer

Electronegativity increases across the period on moving left to right. It decreases on moving down the group. The correct option is Si C N O F

Question 11

The correct decreasing order of atomic radii ( pm ) of Li , Be , B and C is

Accepted Answer

As the atomic number in a period increases, the effective nuclear charge also increases hence, atomic radii along the period decreases. Correct order of atomic radii Li Be B C

Classification of Elements and Periodicity in Properties — Previous Year Questions & Solutions