Question

give answer

1.a compound used as pistachio flavour in ice cream is________
a} vanillin
b} acetophenone
c} muscone
d}butyraldehyde

2.oxidation states of scandium are_______
a} +1,+2
b} +1,+3
C}+2,+3
d}+3,+4

3. In van arkel method for refining zirconium or titanium, the halogen used is_______
a} flurine
b} chlorine
C} bromine
d} iodine

4.A system absorbs 6kj of heat and does 1.5 kj of work on it's surroundings. The change in internal energy is________
a) - 7.5 kj
b) - 4.5 kj
c) +4.5kj
d) +7.5 kj

Answer 1

vanillin,c,a,b options respectively

Answer 2

1) b) acetophenone- from chapter aldehyde, ketone & carboxylic acid

2) c) +2&+3 - from d-block

3) d) iodine- from chapter general principles & process of isolation

4) c)+4.5kJ -from thermodynamics

*Explanation:-*

Change in internal energy(Q) =heat absorbed (q) + work done (w)

  Since, work is done on surrounding by system it is negative.

       Thus, Q = q + w

                 Q = 6 + (-1.5)

                 Q = 6  - 1.5

                  Q= +4.5kJ