JEE Main 2021 · 16 March · evening · Single correct · +4 / −1
The characteristics of elements X, Y and Z with atomic numbers, respectively, 33, 53 and 83 are :
- (a) X and Y are metalloids and Z is a metal.
- (b) X and Z are non-metals and Y is a metalloid.
- (c) X is a metalloid, Y is a non-metal and Z is a metal.
- (d) X, Y and Z are metals.
Answer and solution
Answer (c) X is a metalloid, Y is a non-metal and Z is a metal.
Solution
Chemistry ma’am · 3 steps
Place each atomic number in the periodic table first. Its group and period tell you the character.
- Locate each element. Use the outer electronic configuration to find the period and group. Then read where the element sits relative to the metalloid staircase running from B to At.
Element Outer configuration Position Character X, Z = 33 (As) 4s² 4p³ Period 4, group 15 metalloid Y, Z = 53 (I) 5s² 5p⁵ Period 5, group 17 non-metal (halogen) Z, Z = 83 (Bi) 6s² 6p³ Period 6, group 15 metal - Trend down group 15. Metallic character rises down a group as atoms get larger and lose electrons more easily. Group 15 goes N, P (non-metals), As, Sb (metalloids), Bi (metal), so As and Bi land on opposite sides.
- So. X is a metalloid, Y is a non-metal and Z is a metal, which is option (c).
The idea to keep. For any atomic number, first find its group and period. In the p-block, character moves from non-metal to metalloid to metal as you go down a group or to the left.
Answer from the NTA final answer key. Solution by PrepWiser.