Why might you only see a rainbow when rain is in front of you

Which one of the following is an oxidation-reduction reaction? naoh + hno3 --> h2o + kno3 naoh + hno3 --> h2o + kno3 so3 + h2o --> h2so4 cacl2 + na2co3 --> caco3 + 2 nacl ch4 + 2 o2 --> co2 + 2 h2o al2(so4)3 + 6 koh --> 2 al(oh)3 + 3 k2so4

Using this reversible reaction, answer the questions below: n2o4 2no2 (colorless) (reddish-brown) -as the temperature increased, what happened to the n2o4 concentration? -was the formation of reactants or products favored by the addition of heat? -which reaction is exothermic? right to left or left to right? -if the change of enthalpy of this reaction when proceeding left to right is 14 kcal, which chemical equation is correct? n2o4 2no2 + 14 kcal n2o4 2no2, hr = +14 kcal n2o4 + 14 kcal 2no2 n2o4 2no2, hr = -14 kcal

Benzonitrile (c6h5cn) is reduced to two different products depending on the reducing agent used. treatment with lithium aluminum hydride followed by water forms k, which has a molecular ion in its mass spectrum at 107 and the following ir absorptions: 3373, 3290, 3062, 2920, and 1600 cm-1. treatment with a milder reducing agent forms l, which has a molecular ion in its mass spectrum at 106 and the following ir absorptions: 3086, 2850, 2820, 2736, 1703, and 1600 cm-1. l shows fragments in its mass spectrum at m/z = 105 and 77. propose structures for k and l and choose an explanation for how this could be concluded.