NTA Abhyas JEE Main2020Chemistrys Block ElementsPractice
The ionization energies of Li and Na are 520 kJ m o l - 1 and 495 kJ mol − 1 respectively. The energy required to convert all the atoms present in 7 mg of Li vapours and 23 mg of sodium vapours to their respective gaseous cations respectively are:
Options
- A52 J, 49.5 J
- B520 J, 495 J
- C49.5 J, 52 J
- D495 J, 520 J
Correct answer
B. 520 J, 495 J
Step-by-step solution
For 1 mole Li i.e. 7 g will absorb 520 kJ heat So for 7 mg lithium heat absorbed will be 520 J Similarly for sodium 1 mole Na i.e. 23 g will absorb 495 kJ Heat So for 23 mg sodium heat absorbed will be 520 J