Based on the table, answer the following a) a student claims that the reaction is an oxidation reduction reaction because the oxidation number of carbon changes. do you agree with the claim? b) calculate number of moles of nahco3 present in the mixture in the test tube before the reaction was initiated

 1. No. The oxidation number of C is not changed. This is not a redox reaction since there is no oxidation or reduction.

The balanced equation for the heating of NaHCO₃ is
2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O

Sum of each elements' oxidation number = charge of the compound

For NaHCO₃,
Na = +1           H = +1             O = -2          C = a

1 + 1 + a + (-2) x 3 = 0
       2 + a - 6           = 0
                        a     = +4      

For Na₂CO₃,
  Na = +1         O = -2          C = b

1 x 2+ b + (-2) x 3 = 0
       2 + b - 6          = 0
                        b    = +4  

For CO₂,
  O = -2          C = z
 
            z + (-2) x 2 = 0
              z - 4          = 0
                        z    = +4  

a = b= z = +4

Hence, oxidation number of C is not changed.

2. The reaction is
                        2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O

By drying agent, the produced H₂O is removed by absorbing.

Then mass of produced H₂O = Final mass of drying agent - initial mass
                                                 = 2.303 g - 2.134 g
                                                 = 0.169 g
Molar mass of H₂O = 18 g/mol

Hence, moles of produced H₂O = 0.169 g / 18 g/mol
                                                   = 9.39 x 10⁻³ mol

The stoichiometric ratio between NaHCO₃ and H₂O is 2 : 1

Hence, moles of NaHCO₃ = moles of H₂O x 2
                                          = 9.39 x 10⁻³ mol x 2
                                          = 0.01878 mol

Hence, 0.01878 moles of NaHCO₃ present initially.

(Assume that all NaHCO₃ are heated during 10 minutes)

Mass is the amount of matter in an object.  weight is the measurement of the pull of gravity on an object.  say for example, you travel to the moon which has a different gravitational field compared to the gravitational field of earth. (gravitational fields: earth = 1, moon = 0.165)  now when you are on the moon, the pull of gravity on you is different than on the earth. and as weight is the measurement of the pull of gravity on an object, that means yes, your weight can and will change on the moon.  however, on the moon, on earth or even on jupiter, the amount of mass inside of you remains the same. meaning your physical mass remains constant.  in conclusion it is possible for your weight to change as your mass remains constant.