The 3s state of Na has an energy of -5.14 eV. Its effective nuclear charge is ( )
举一反三
- As far as its nuclear program is concerned, what does Iran maintain（） A: It’s for world peace and development. B: It’s for the protection of the country. C: It’s for peaceful energy purposes. D: It’s for anti-terrorism purposes.
- Equilibrium is the condition of a system when neither its state of motion nor its internal energy state tends to change with time. A: 正确 B: 错误
- In U.S.A., Each state of the U.S.A. has its own state constitution.
- 在气体放电管中，用能量为12.1 eV的电子去轰击处于基态的氢原子，此时氢原子所能发射的光子的能量只能是 A: 12.1 eV． B: 10.2 eV． C: 12.1 eV，10.2 eV和 1.9 eV． D: 12.1 eV，10.2 eV和 3.4 eV．
- Research has shown that the larger the team, the more effective its performance.