Arrange the following in the decreasing order of their melting points:
I. Heptane II. Octane
III. Nonane IV. Decane
IV > II > III > I
IV > III > I > II
I > II > IV > III
II > III > I > IV
Which of the following is not a cumulated diene?
Hexa - 2 , 3 - diene
Penta - 1 , 3 - diene
Hexa - 1 , 2 - diene
Penta - 2 , 3 - diene
In the eclipsed conformation of ethane, the dihedral angle between the hydrogen atoms of adjacent methyl groups is :
60°
120°
0°
180°
The major product of the addition of water molecule to propyne in the presence of mercuric sulphate and dilute sulphuric acid is :
ethanal
2-propanol
propane
propanone
Which of the following statements is not an essential feature of an optically active molecule ?
It will rotate the plane of polarised light
It will have a non-superimposable mirror image
It will have no element of symmetry
It will have an asymmetric carbon atom
The reagent which could distinguish between 1-hexyne and 1-hexene is :
Ag
KMnO4
Br2 in CCl4
H2SO4
Choose the correct reagent required to carry out the transformation :
Zn + conc. HCl
conc. H2SO4
Li then H2O
H2/Pt
The heat liberated when 1.89 g of benzoic acid is burnt in a bomb calorimeter at 25°C and it increases the temperature of 18.94 kg of water by 0.632°C. If the specific heat of water at 25°C is 0.998 cal/g-deg, the value of the heat of combustion of benzoic acid is
881.1 kcal
771.2 kcal
981.1 kcal
871.2 kcal
B.
771.2 kcal
Weight of benzoic acid = 1.89 gm
Temperature of bomb calorimeter = 25C = 298 K
Mass of water (m) = 18.94 kg = 18940 gm
Increase in temeperature (t) = 0.632C
Specific heat of water (s) = 0.998 cal/g-deg.
We know that heat gained by water or heat liberate by benzoic acid (Q) = mst = 18940 0.998 0.632 = 11946.14 cal
Since, 1.89 gm of acid liberates 11946.14 cal of heat.
Therefore heat liberated by 122 gm of acid ( mol. wt. of benzoic acid)
= = 771126.5 cal = 771.12 kcal.