Question

1. Which one of the following is not a state function ?

   		change in temperature
   		internal energy
   		enthalpy
   		heat

1. Calculate ΔH for the following reaction

     C₂H₄ (g)   +   6 F₂   → 2 CF₄ (g)   + 4 HF (g)

   from

      H₂ (g ) + F₂ (g)    → 2 HF (g)      ΔH  =  - 537 kJ

   C (s) + 2 F₂ (g)   → CF₄ (g) ΔH = -680 kJ

   2 C (g) + 2 H₂ (g)   → C₂H₄ (g) ΔH = + 52 kJ

   		-719 kJ
   		- 815 kJ
   		-1165 kJ
   		-2486 kJ

1. Calculate ΔH^o for

      C₆H₆ (l) + 15/2 O₂ (g)   →   6 CO₂ (g) +   3 H₂O (l)

   from

         ΔH^o_f C₆H₆ (l)   =   49.0 kJ

   ΔH^o_f CO₂ (g) = - 393.5 kJ

   ΔH^o_f H₂O (l) = -285.8 k J

   		- 2361 kJ
   		- 1208.7 kJ
   		- 3169.4 kJ
   		- 1454.6 kJ

1. Which atom is the smallest ?

   		O
   		B
   		C
   		Cl

Answer 1

is not a Auss- Heat is not a a system, it Ом a state function Therefore, option (d heat is correct Explanation State function is independent of pathways taken to get a specific value. Heat State function because it is only to traus fer energy in or out of depends pathways. On the other hand, change in temperature, internal energy and enthalpy is state function because temperature is dependent final and initial values, not on the path taken. Internal energy is a point function that is independent of the path followed to change the state of the system. And enthalpy is state function because it is defined in thms of state functions. U, P and u are all state functions. Their values depend only of the system and not on the paths taken on the a on the state to reach their values. Enthalpy is defined as H= U+PV.

) Ans: AH for the reaction is 2486 KJ So, Option d), - 2486 kJ is correct Explanation! The given reaction ist Chu (g) + 6 Fax LC Fu (g) + 4 H F (g) DHEAM (products) – Some (see that > (21-680kr) + 46+69.5) - 152ks ] = [-1360 kJ-1074K5] - [5QkJ] -2434 KJ-52k J - - 2486 kJ Ans! Oh is F3169.4 kJ So, option C - 3169.4 KJ is correct 'f Explanation : DH = some ( products) – Eon; (reacteuts)} + [6C-393.5 kJ)+36-285.8kJ)]-[49 ku] = (-2361 KJ – 857.4 kö]-[49K5]

(3 OH-3218.4 KJ -49 kJ SH - 3267.4 kJ ř -31.69.4K J a As we move Ang:- Tolis ol is the smallest So, the option a, o is correct. Explanation : 0 is smallest because as we move down the group, atomic size increases as one shell is added progressively to the succeeding element's atom. from left to right along period in the Periodic table, the atomic size progressively decreases because number of shells remain the same but electronegative increases due to which the outle- most electrows in the outer most shell are pulled inwards which leads to overall decrease in the size of Oxygen belongs to group 16 and lies in period 2 and have the position right side to B and C. That's why, o is the smallest. atou.

th On the other hand, ce is the 17 element on the periodic table. It is located in period 3 and group 17. So, it is not the smallest atom from given atoms.