The calcium salt E has the formula CaCxOy. When 1.00 g of E was heated strongly, 386 cm³ of a mixture of two gases (measured at 298 K and 1.00 x 10⁵ Pa) was produced, and 0.438 g of a white solid remained. The addition of excess NaOH(aq) to the gaseous mixture caused its volume to decrease by 193 cm³.

(i) Calculate the average Mr of the gaseous mixture.
(ii) Suggest the identity of the gas that reacted with NaOH(aq). (CO₂)
(iii) Hence, calculate the Mr of the other gas in the gaseous mixture, and suggest its identity.
(iv) Suggest the formula of E and write a balanced equation for its thermal decomposition.
(v) Predict whether the magnesium analogue of E, MgCxOy, would decompose at a higher or lower temperature compared to E? Explain your answer.