Washing soda is: MCQ with Answer and Explanation

Explanation:
Atomic number 17 is chlorine. Electronic configuration: 2,8,7. Period number = number of shells = 3. Group number = 10 + valence electrons (for p-block elements) = 10+7 = 17. Hence Group 17 (halogens), Period 3. Group 1 has 1 valence electron, Group 16 has 6, Group 18 has 8 (except He). Simple method: period = number of shells.

Explanation:
According to the reactivity series, zinc is more reactive than copper, so Zn displaces Cu: Zn + CuSO₄ → ZnSO₄ + Cu. Silver, gold, and mercury are less reactive than copper and cannot displace it. Reactivity: K > Na > Ca > Mg > Al > Zn > Fe > Pb > Cu > Ag > Au. Displacement reactions are used in metallurgy and galvanic cells. The blue color of CuSO₄ fades as copper is deposited.

Explanation:
Sodium has the electronic configuration [Ne]3s1. After losing one electron to form Na+, it achieves a highly stable noble gas configuration ([Ne]). Removing a second electron from this stable core requires an exceptionally large amount of energy. Thus, sodium has the highest second ionization energy among these elements.