3 question on Rate Mechanisms

  Please show all work and keep things as simple as possible.  This is a first year general chem class.

The Rate Law.  
a.  A possible mechanism for the reaction between H2 and CO is shown below, where RDS is the rate-determining step.  What is the rate law for the overall reaction?

H2  2 H          
H + CO  HCO          (RDS)
H + HCO  H2CO

b.  A possible mechanism for the reaction of NO with O2 is shown below, where RDS is the rate-determining step.  What is the rate law for the overall reaction?

NO + NO  N2O2
N2O2 + O2  NO2 + NO + O          (RDS)
NO + O  NO2


Reaction Mechanisms.  Four possible mechanisms for the reaction 2 NO2Cl 2 NO2 + Cl2 are shown below, where RDS is the rate-determining step.  The experimentally determined rate law is first-order in NO2Cl.  Explain which mechanisms are reasonable and which are not reasonable.  

Mechanism 1
NO2Cl + NO2Cl 2 NO2 + Cl2          

Mechanism 2
NO2Cl NO2 + Cl           (RDS)          
NO2Cl + Cl NO2 + Cl2          

Mechanism 3
NO2Cl NO + OCl
NO2Cl + OCl NO3 + Cl2          (RDS)
NO + NO3 2 NO2

Mechanism 4
NO2Cl N + O2Cl          (RDS)
O2Cl + NO2Cl NO4 + Cl2          
NO4 + N N2O4


Catalysis.  Acetaldehyde can undergo catalytic decomposition according to the mechanism below:
CH3CHO + I2  CH3I + HI + CO           (RDS)
CH3I + HI  CH4 + I2

Use the mechanism to determine 1 the overall chemical equation, 2 the catalyst, 3 the intermediates, and 4 the rate law.