Which of the following compounds is insoluble in water? Which of the following i

Question

Which of the following compounds is insoluble in water? Which of the following is weak base? What is the oxidation state of C in HCO2H? 27. Which of the following metals is capable of reducing Fe2+ ions? 29. If a metal dissolves in HCl or H2SO4, bubbling is observed. The bubbling is due to the formation of gas. 30. A 43.21-g sample of an unknown metal is heated to 110.8 degree C and dropped into 67.28 g of water initially at 24.2 degree C. The mixture reaches a temperature of 29.7 degree C. What is the specific heat of the metal in J/g degree C?

Explanation / Answer

25. Answer - D

Calcium carbonate is insoluble in water because it is extremely stable as a solid and water doesn't have sufficient solvating capability to cause the ions to separate and come into solution.

26. Answer - D

NH3 is a weak base becoz it readily dissolves in water and combines with H+ to form NH4+ .Hence it reduces H+ concentration and becomes a base.

27. Answer - D

Let oxidation state of C be 'x'

Therefore,
   1+x-2-1 =0
   => x =+2

28. Answers - B ,D ,E (Cu, Ag, Co)

the metals that can reduce Fe are those metals that have high reduction potentials than iron, In the sense the metals that are above iron in the standard electrode potential can reduce iron.

29. Answer - D

2M + 2HCl --> 2MCl + H2 (bubbling)

30. Answer - C

Thermal equilibrium,

Heat lost by the metal = heat gained by the water

S1 = ? , M1 = 43.21g T1 =110.8 + 273 = 383.8K   

S2 = 4.184J/goC , M2 = 67.28g T2 = 24.2 + 273 = 297.2K

final temperature =  29.7+273 = 302.7K

Q =MS(delta (T))

delta(T) = final tempertaure - intial temperature

M1S1(delta(T)) = M2S2(delta(T)

43.21 * S1 * (383.8 - 302.7) = 67.28 * 4.184 * (302.7 - 297.2)

S1 = 0.441 J/goC

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