DU 18-19

$CH_3(CH_{2)2}CH=CHCO_2H$

$CH_3(CH_{2)4}CH_2COCH_2CH_3$

$CH_3CH_2CO_2(CH_2)_4CH_3$

$CH_3(CH_2)_4CO_2CH_2CH_3$

nitrogen and oxygen

oxygen and nitrogen

potassium and oxygen 

nitrogen and potassium

$1-\frac{1}{2}\cos2A$

$1+\sin2A$

$1+3\cos2A$

1+1 cos2A$1+\frac{1}{2}\cos2A$

$CH_3CH_2COOH$

$ClCH_2CH_2COOH$

$Cl_2CHCOOH$

$CH_3COOH$

$Mg^{2+}<Na^+<Ne$

$Mg^{2+}<Ne<Na$

$Na^+<Mg^{2+}<Ne$

$Mg^{2+}>Na^+>Ne$