. Choose the correct answer from the option: An element in Period 3 whose electronic affinity is zero. A. Neon B. Sulphur C. Sodium D. Argon


(a) Choose the correct answer from the option:

An element in Period 3 whose electronic affinity is zero.

A. Neon B. Sulphur

C. Sodium D. Argon 

(b) Give reason:

(i) Ionisation potential of the element increases across a period.

(ii) Alkali metals are good reducing agents. 

(c) There are three elements E, F, G with atomic numbers 19, 8 and 17 respectively.

Classify the above elements as metals and non-metals.

(d) Name: A metal present in Period 3, Group I of the periodic table.

 

 

 

Best Answer

(a) D. Argon, as it’s a inert gas having octet configuration

(b) (i) The atomic radius decreases across a period. Due to this, attraction between the nucleus and the electron increases. Hence, it results in an increase in the ionisation potential.

(ii) Alkali metals have a greater tendency to lose electrons so, they are good reducing agents.

(c)

Electronic configuration of E with atomic number 19 = 1s22s22p63s23p64s1

Since there is only one valency electron, E is a metal.

Electronic configuration of F with atomic number 8 = 1s22s22p4

As the number of valence electron is 4, F is a non-metal.

Electronic configuration of G with atomic number 17 = 1s22s22p63s23p5

The number of valence electrons is 5, so G is a non-metal.

(d) The metal present in Period 3, Group I of the periodic table is Sodium (Na).

 

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