①1s22s22p63s23p4 ②1s22s22p63s23p3 ③1s22s22p3 ④1s22s22p5
则下列有关比较中正确的是( )
A:第一电离能:④>③>②>①
B:原子半径:④>③>②>①
C:电负性:④>③>②>①
D:最高正化合价:④>③=②>①
People usually____in some western countries when they see each other.
下列计算正确的是( )
已知P=715m-1,Q=m2-815m(m为任意实数),则P、Q的大小关系为( )